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App note: HT45F3630 power tool speed control switch application example

Posted on Sunday, June 25th, 2017 in app notes by DP | No Comments

an_holtek_an0427e

All in one motor control MCU HT45F3630 from Holtek. Link here (PDF)

Aimed at the motor speed control product application area, HOLTEK has developed the HT45F3630, which is commonly used in electric drills, electric screwdrivers, lawn mowers and other similar product applications. This MCU provides a group of PWM high voltage and large current output pins which can directly drive Power MOS transistors to reduce their switching losses. Additionally, the device includes integrated over current protection and detection functions and an amplifier which allows the input signal to be amplified by 51 times, requiring a lower value current sense resistance value which will increase the overall efficiency and extend the operating time. When an over current event occurs, the PWM switching will be shut off by hardware to achieve immediate protection.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, June 23rd, 2017 in Free PCBs by DP | 1 Comment

BP

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

(more…)

Dual purpose spot welder with pulse duration control

Posted on Thursday, June 22nd, 2017 in DIY by DP | No Comments

SpotWelder1-600

Kerry Wong published a new build:

I had wanted to make a spot welder for a while. Most of the DIY spot welders use a momentary switch the primary side of the microwave oven transformer (MOT). Due to the simplicity of this design, it is very simple to make. This design however, has some inherent safety issues as the momentary switch is typically within reaching distance of the operator (unless a foot switch is used) and inadequate insulation could increase electric shock risk. Further more, the current flowing through the primary winding can significantly exceed the current rating of the switch and cause the switch to fail. Due to the inductive nature of the winding, the switch can sometimes arc over and pose significant risk to the operator.

Project info at Kerry Wong’s blog.

Check out the video after the break. (more…)

DIRTY CABLES: Cheap custom cables available now

Posted on Thursday, June 22nd, 2017 in cables, components, DirtyPCBs.com by Ian | 2 Comments

DirtyPCBs

Dirty Cables is a drag and drop cable builder that gives you access to cheap custom cable services from China. Build a custom cable, get an instant quote, and checkout. Your custom cables should ship in 3 to 7 work days.

Huaqiangbei is full of cheap custom cable vendors with a big pile of samples on their booth. We tried to put the pile online so you can get cheap cables without making a trip to China!

cable-pile-2

We excavated the cable sample piles to see which connectors are common, cheap and readily available in the Chinese market. We bought bundles of everything and identified 17 common cable-to-cable and cable-to-board connector families to add to Dirty Cables. Read more about the different cable families here.

Cables are probably best understood by touching them yourself, so we put together a Dirty Cables Sample Kit that includes examples of each cable and connector. The kit is available in the store for $9.95.

In the coming weeks we’ll document a few more common and cheap connectors that didn’t quite fit in the first sample kit:

  • Crimp terminals: ring and spade ( M3/3.2mm, M4/4.2mm, M5/5.2mm, M6/6.2mm), two-part blades (2.8mm, 4.8mm, 6.3mm)
  • Coaxial power connectors (5.5×2.1mm, various)
  • LED strip connectors (3528/8mm, 5050/10mm, etc)

Dirty Cables is highly experimental. If pricing seems way off, if you find bugs, or if we’re missing your favorite connectors, please give us a shout in the comments or through the contact form.

DIRTY CABLES: What’s in that sample pile?

Posted on Thursday, June 22nd, 2017 in cables, components, DirtyPCBs.com by DP | 5 Comments

cable-pile

Massive sample piles advertise the custom cable manufacturers in Huaqiangbei market. A sketch and a few part numbers is enough to get a quote on the spot. These piles reveal which connectors are standard and readily available in the Chinese manufacturing ecosystem. To avoid sourcing problems and production delays its probably best to stick with one of these common connectors in your projects.

We grabbed a sample of every cable from the piles in the SEG and HQ Mart markets, then verified the actual model against datasheets. In this post we look at the common connector families available from multiple manufacturers. Sometimes market traders call the connectors by an unofficial part number, we’ve included these to help you communicate with Chinese vendors.

Continue below for an overview of the 17 most common cable and connector types from the Chinese market. Try out Dirty Cables to build your own custom cables, and grab the Dirty Cables Sample Kit to explore these connectors with your own hands.

Parts of a cable

Crimp housing

crimp-housing

A crimp housing holds the metal crimp contacts and cable wires, and mates with a PCB or cable mount connector. The most recognizable measurement of a crimp housing is pitch, the distance between pins. Common crimp housing pitch ranges from 1mm to 4.2mm.

Crimp contacts

crimps

Crimp contacts are the metal bits that mate cable wires to connectors. Crimp materials and coatings vary, which impact the maximum power rating of the cable. Nickel plated crimp contacts are by far the most common default option. A few connectors, mostly IDC, generally have gold plated contacts by default.

crim-machine

Reels of crimp contacts and wire load into a crimping machine. The machine strips the wire, attaches the crimp contact, and cuts the wire to length. Specific tooling is needed to attach and cut each type of crimp. Manufacturers can’t attach a crimp without the right tooling for their crimp machines.

Wire

wire-2

Cable wire is generally multiple strands of copper wire that have been tinned with solder and coated in insulation. Common colors are available: red, orange, yellow, green, blue, purple, pink, brown, white, gray, and black. Wire size effects the maximum voltage and current a cable can carry, common cable wire sizes range from 32AWG to 16AWG (smaller AWG = bigger wire).

wire-ribbon-rainbow-gray-10

Some connectors use flat ribbon cables, generally with gray or rainbow colored insulation. Common sizes:1.27mm, 1mm, and 0.635mm.

PCB mount connectors

pcb-mount-connector

A connector mates a cable to a circuit board or another cable. Connectors may be polarized so the cable only fits one direction, or have locking features to keep the cable from coming loose. Cables may attach to the PCB from the top (top entry) or the side (side entry).

Cable to board connectors

cable2pcb

Most cables in the market connect to a circuit board (cable to board), some connect two cables (cable to cable). A few will do both. First let’s look at the common cable to board connectors.

CRHO

CRHO254-all

Let’s call this the simplest cable in the market. It mates directly with standard 2.54mm (0.1”) pitch pin header. It’s the only connector we found that isn’t polarized, it can attach in any direction.

Frequently called a DuPont connector, even in Chinese, but the current common version seems to be compatible with TC Connectivity’s AMPMODU IV series. We’re going to call it CRimp HOusing (CRHO) because it’s the most bog standard thing in the market. CRHO is borrowed from the amazing and unloved OOMP project.

Pin header PCB mount connectors are available in through hole (PTH) and surface mount (SMD), as well as various colors.

Series Pitch Pins Wire Size Vmax Amax
CRHO 2.54mm 1-40 28-22AWG 250VDC 3A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
CRHO-xx HDR-2.54-xxX1P HDR-2.54-xxX1P-RA HDR-2.54-xxX1P-SMD HDR-2.54-xxX1P-RA-SMD

KF2510

KF2510-all

KF2510 is basically a keyed CRHO style housing. It mates with 2.54mm (0.1”) pitch keyed board mount connectors. It also fits on 2.54mm (0.1”) pin header, but without the polarity protection of the keyed connector.

The crimp housing and board connectors come in beige and white, which may have different maximums and tolerances so be sure to consult the datasheet.

Series Pitch Pins Wire Size Vmax Amax
KF2510 2.54mm 2-16 30-22AWG 250VDC 3A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
KF2510-xxY KF2510-xxA KF2510-xxP

SH 1.0mm (JST compatible)

SH10-all

A 1.0mm pitch cable compatible with the JST SH series is the smallest we found in the market. At over 1 RMB per sample it was also among the most expensive cables.

Series Pitch Pins Wire Size Vmax Amax
SH 1.0mm 2-20 32-28AWG 50VDC 1A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
SHR-xxV-S-B BmxxB-SRSS-TB SmxxB-SRSS-TB

51021 1.25mm (Molex compatible)

51021-all

This one is hard to tie down, and it seems to be a widely confused part. Chinese market traders and most of Taobao call this “SH 1.25”, as in a 1.25mm version of the JST SH 1.0mm connector above. We’ve also seen it called A121-xxY/A1251-Hxx, which may be a duff manufacturer part number.

This is actually a Molex 1.25mm “PicoBlade” 51021 compatible part. It’s no wonder Molex parts get nick names. Molex has a knack for making really crappy part numbers, and has even “upgraded” to new numbers that are worse than the old numbers.

Series Pitch Pins Wire Size Vmax Amax
51021 1.25mm 2-15 32-28AWG 125VDC 1A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
51021-xx00 53047-xx10 53048-xx10 53398-xx71 53261-xx71

ZH 1.5mm (JST compatible)

ZH15-all

A 1.5mm pitch cable compatible with the JST ZH series. A vendor said this isn’t a commonly requested cable type, but there isn’t a shortage of suppliers in the market or online.

The through-hole mount connectors come in two versions for different PCB thickness. Use BxxB-ZR-3.4/SxxB-ZR-3.4 for standard 1.6mm thick PCBs, or BxxB-ZR/SxxB-ZR for thinner 0.6-1.2mm thick boards.

Series Pitch Pins Wire Size Vmax Amax
ZH 1.5mm 2-13 32-26AWG 50VDC 1A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
ZHR-xx BxxB-ZR(-3.4) SxxB-ZR(-3.4) BxxB-ZR-SM4-TF SxxB-ZR-SM4A-TF

PH 2.0mm (JST compatible)

PH20-all

2.0mm pitch cable compatible with JST PH series. 2.0mm saves a bit of space over standard 2.54mm pitch connectors, but is still easy for most people to hand solder.

Series Pitch Pins Wire Size Vmax Amax
PH 2.0mm 2-16 32-24AWG 100VDC 2A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
PHR-xx BxxB-PH-K-S SxxB-PH-K-S BxxB-PH-SM4-TB SxxB-PH-SM4-TB

XH 2.5mm (JST compatible)

XH250-all

A 2.50mm cable compatible with the JST XH series. 2.50mm != 2.54mm, pitch is actually 2.50mm. Many suppliers incorrectly list this as 2.54mm part. Despite the size difference, the connectors will generally still fit 2.54mm breadboards and pin headers.

An SMD top entry PCB mount connector is not an official part in the JST datasheet, but it’s widely available in the Chinese market. We named this connector BxB-XH-SM4-TB following the JST part numbering system, but note that it is not an official part number.

There are two oddities in this family. An XHP-20 crimp housing and connector exists with 20 pins in a 10x2P configuration. The through-hole side entry PCB mount connector also comes in a short shroud (7.2mm) version (SxB-XH-A-1). These specialty options don’t seem to be available in the Chinese markets.

Series Pitch Pins Wire Size Vmax Amax
XH 2.50mm 1-16 30-22AWG 250VDC 3A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
XHP-xx BxxB-XH-A SxxB-XH-A(-1) BxxB-XH-SM4-TB SxxB-XH-SM4-TB

CH 3.96mm

CH396-all

A 3.96mm pitch nylon connector that the market vendors call “CH”. Heavy duty crimps and heavy duty connectors make this a good choice for power connections. It has a retention “bump” that helps secure the connection. The retention bump also helps polarize the connection, but nylon is flexible and the connector could be installed backwards with enough force.

This part is not from JST, despite a similar part number. Some duff manufacturers list this as 2139-xxY, similar to a Molex part number, but that isn’t an exact match for the board mount connectors. We use the market vendor name “CH”, short for CHina connector.

There are two versions of the side entry connector. 2139-xAWG has a 4.3mm extended length pin. This version is listed at several Taobao shops, but it was always out of stock and all our orders were eventually canceled.

Series Pitch Pins Wire Size Vmax Amax
CH 3.96mm 2-16 24-18AWG 250VDC 7A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
2139-xxY 2139-xxA 2139-xxAW(G)

VH 3.96mm (JST compatible)

VH396-all

A 3.96mm pitch locking connector compatible with the JST VH series. This is another connector with heavy duty crimp contacts and connectors that is ideal for power supplies. Keyed to protect polarity, locking to secure in place.

The datasheet lists an -M version with a safety retainer. We could not locate this part in the market.

Series Pitch Pins Wire Size Vmax Amax
VH 3.96mm 2-11 16-22AWG 250VDC 10A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
VHR-xxN BxxP-VH(-FB-B) BxxPS-VH

Insulation Displacement Connectors

IDC

Insulation displacement connectors (IDCs) are a cable to board connection system that doesn’t use crimp contacts. Teeth in the connector cut through the insulation of a ribbon cable and make contact with the wires inside.

These connectors have been around forever, but there doesn’t seem to be a solid part numbering system. Generally the displacement connector part number is FC. The PCB mount connector is DC3 (DC2 and DC4 are variants with locks and wings and such). We created our own part numbering system based on this convention that takes into account newer, smaller 2.0mm and 1.27mm pitch IDC versions.

IDC 2.54mm

IDC254-all

Bog standard 2.54mm IDC and mating shrouded header. It has a polarizing key that only fits one way, but there’s no retention mechanism aside from the friction fit. Fits 1.27mm ribbon cable.

Series Pitch Pins Wire Size Vmax Amax
IDC 2.54mm 6-64 1.27mm 100VDC 2A
Mating Connectors Through-hole Surface Mount
IDC connector Top Entry Side Entry Top Entry Side Entry
IDC-FC-2.54-xx IDC-DC3-2.54-xx-PTH IDC-DC3-2.54-xx-RA-PTH IDC-DC3-2.54-xx-SMD

IDC 2.0mm

IDC200-all

Smaller. An even metric measure. What’s not to love? 2.0mm IDCs save a bit of board space, but are still easy to hand solder for most people.

Slightly more expensive than common 2.54mm IDCs. Fits 1.0mm ribbon cable, rainbow color may not be available.

Series Pitch Pins Wire Size Vmax Amax
IDC 2.0mm 10-50 1.0mm 50VDC 1.5A
Mating Connectors Through-hole Surface Mount
IDC connector Top Entry Side Entry Top Entry Side Entry
IDC-FC-2.0-xx IDC-DC3-2.0-xx-PTH IDC-DC3-2.0-xx-RA-PTH IDC-DC3-2.0-xx-SMD

IDC 1.27mm

IDC127-all

1.27mm pitch IDCs are the smallest available in the market. Fewer manufacturers and suppliers than 2.0mm and 2.54mm IDCs means they’re more expensive and harder to source. The right-angle through-hole connector was only available as a special order of MOQ (200 pieces).

Fits 0.635mm ribbon cable, rainbow color may not be available.

Series Pitch Pins Wire Size Vmax Amax
IDC 1.27mm 8-80 0.635mm 50VDC 1A
Mating Connectors Through-hole Surface Mount
IDC connector Top Entry Side Entry Top Entry Side Entry
IDC-FC-1.27-xx IDC-DC3-1.27-xx-PTH IDC-DC3-1.27-xx-RA-PTH IDC-DC3-1.27-xx-SMD

Cable to cable connectors
cable2cable

Some cables connect to other cables. These are common in hobby R/C batteries and wiring harnesses for panel mount switches, lights, and connectors.

Receptacle housing

If the cable connects to another cable the common terms plug and receptacle seem to be used. Manufacturers use different criteria to distinguish a plug and receptacle. A JST receptacle holds male crimp pins, while the JST plug holds the female crimp sockets (see datasheet excerpt above). Molex, however, calls the male crimp housing (with female crimp sockets) a receptacle and the female crimp housing (with male crimp pins, same as PCB mountable connector) a plug.

RCY 2.5mm (JST compatible)

plug-receptacle

2.5mm (not 2.54mm) JST RCY series compatible connector. Commonly used as a battery connector and only available in a 2 pin version. Market vendors simply call this “JST 2P”.

Always red. A white version exists in the datasheet but has not been spotted in China.

Series Pitch Pins Wire Size Vmax Amax
RCY 2.50mm 2 28-22AWG 250VDC 3A
Mating Connectors Through-hole Surface Mount
Receptacle Plug Top Entry Side Entry Top Entry Side Entry
SYR-02T SYP-02T-1

SM 2.5mm (JST compatible)

SM250-all

2.5mm (not 2.54mm) JST SM series compatible connector. High pin count cable to cable connector with polarization key and retention lock.

An 18 pin version exists in a 9x2P configuration that is not available in the market.

Series Pitch Pins Wire Size Vmax Amax
SM 2.50mm 2-12 28-22AWG 250VDC 3A
Mating Connectors Through-hole Surface Mount
Receptacle Plug Top Entry Side Entry Top Entry Side Entry
SMR-xxV-B SMP-xxV-BC

Cable to cable & cable to board

Molex 5557 and 43025 series power connectors have mating cable mount plug connectors and PCB mount connectors.

5557 4.2mm (Molex compatible)

5557-all

Molex 5557 4.2mm “Mini-Fit” compatible connectors are familiar from ATX power supplies and computer motherboards. The crimp receptacle is 5557-xxR. It mates with cable to cable plug 5559-xxP, and through-hole PCB mount connectors 5566-xxA and 5569-xxA.

The datasheet lists black crimp housings (5557-xxR-BL,5559-xxP-400), but they’re not common in China.

Series Pitch Pins Wire Size Vmax Amax
5557 4.2mm 2-24 16-28AWG 600VDC 9A
Mating Connectors Through-hole Surface Mount
Receptacle Plug Top Entry Side Entry Top Entry Side Entry
5557-xxR 5559-xxP 5566-xxA 5569-xxA

43025 3.0mm (Molex compatible)

43025-all

3.0mm Molex “Micro-Fit” 43025 series compatible connector. This is a smaller 3mm version of the 5557 series above. In fact, Market and Taobao suppliers call this “5557 3.0”.

The crimp receptacle is 43025-xx00. It mates with cable to cable plug 43020-xx00, and through-hole PCB mount connectors 43045-xx12 and 43045-xx00. Through-hole PCB mount connectors are widely available in the Chinese market. Molex sells a surface mount version too, but we can’t find cheap domestic production so we’re not including it here.

Series Pitch Pins Wire Size Vmax Amax
43025 3.0mm 2-24 20-30AWG 600VDC 5A
Mating Connectors Through-hole Surface Mount
Receptacle Plug Top Entry Side Entry Top Entry Side Entry
43025-xx00 43020-xx00 43045-xx12 43045-xx00

Debug connectors

Temporary connectors like test probes, alligator clips, and pin header fall into this category.

CRHO-M 2.54mm

CRHO-M-all

A male pin crimp contact that fits into the standard CRHO housing, we’re calling it CRimp HOusing Male (CRHO-M) for short. Useful for breadboards and temporary connections to female headers.

In theory these could be made for any number of pins supported by the CRHO cable to board family, but in practice we only found single pins in the market.

Series Pitch Pins Wire Size Vmax Amax
CRHO-M 2.54mm 1 28-22AWG 250VDC 3A
Mating Connectors Through-hole Surface Mount
Crimp Housing Top Entry Side Entry Top Entry Side Entry
CRHO-M-xx FHDR-2.54-xxX1P

Note on cable maximum, tolerances

CH-example

Most of the connectors we found are compatible with popular designs from Molex and JST, but we assume they’re made by secondary manufacturers (duff manufacturers). In this post we list specs from the original manufacturer’s datasheet where available. Tolerances and rating may not be the same for the duff parts from the market. Be sure to leave wide safety margins for current and voltage when working with no-name Chinese cables, and inspect the final cable to ensure it’s properly suited for the intended load.

Dirty Cables: Get your own custom cables

DirtyPCBs

Get cheap custom cables for your project, direct from Huaqiangbei. Use the Dirty Cable creator to drag and drop wires and connectors into a cable and price custom cables from quantity 100. The example shown here is a 4 pin 1.0mm SH compatible connector broken out to 4 single pin 2.54mm CRHO-M connectors, only $0.23 each at quantity 100!

Touch it yourself: Dirty Cables Sample Pack v1.0

sample pack

Need to get up close and personal with all these cables and connectors yourself? The Dirty Cables Sample Pack has all of the cable types covered in this post, plus all mating cable and PCB mount connectors. Grab it in the store for $9.95.

Taking it further

In the coming weeks we’ll cover three more categories of less common cables and connectors: crimp terminals, coaxial power connectors, and LED strip sockets.

Seeed Studio Summer Sale! — Enjoy 10% OFF purchases over $100!

Posted on Wednesday, June 21st, 2017 in News by DP | No Comments

summer22

Enjoy 10% OFF your purchase of $100 or more at Seeedstudio Bazaar!

Let’s celebrate summer time with a screaming deal on Seeedstudio Bazaar! You can enjoy 10% Discount for order product value above US$100.

Promo code:
SEEEDSUMMER

Promotion Time:
From June 13th to June 30th (GMT+8)

The coupon will be expired on June 30th.

Items:
All Bazaar items! (Bundle sales items are excluded.)

Visit Seeed Studio’s promo page for details.

How to: STM32F103C8T6 as an USB device (Virtual serial port / CDC)

Posted on Wednesday, June 21st, 2017 in how-to, USB by DP | No Comments

In this video Hugatry shared detailed instructions of how to use the STM32F103C8T6 as an USB device with virtual serial port:

Cheap STM32F103C8T6 development board
Blue STM32F103C8T6 development boards, also known as “BluePill”, are cheap way to get started with 32bit ARM microcontrollers. The STM32 development board can sometimes be bought for less than $2 and ST-LinkV2 compatible programmer and debugger doesn’t cost much more than that either.
The STM32F103C8T6 has nice amount of flash and RAM, runs at 72MHz and best of all: It has built-in USB. It is possible to program these STM32 boards to act as an USB devices, without “FTDI chip”. In this post and in the embedded video I will teach step by step how to use the STM32F103C8T6 as an USB device, in particular a virtual serial port.

More details at Hugatry’s HackVlog.

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, June 20th, 2017 in Free PCBs by DP | No Comments

BP

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Arduino data logger update

Posted on Tuesday, June 20th, 2017 in Arduino, DIY by DP | No Comments

s-teriminalminiloggerthecavepearlproject-600

An update on Edward Mallon’s Arduino data logger project we covered previously:

If you need a logger with a cheap durable housing, it’s still hard to beat the Dupont-jumper build released in 2016. But sometimes I need more of a bare-bones unit for bookshelf test runs while I shake down a new sensor. I can whip up a breadboard combo in about twenty minutes, but they can stop working if I bump one of the wires by accident. I’ve lost SD cards from this half way through a long term test, and I’ve also run into issues with noise & resistance from those tiny breadboard contact points.
To address this problem I’ve come up with a new configuration that uses a screw-terminal expansion shield originally intended for the Arduino Nano. This requires a modest bit of soldering, and after some practice, between 1-1.5 hours to finish depending on how many “extras” you embed.

Read more details at his blog here.

Free PCB Sunday: Pick your PCB

Posted on Sunday, June 18th, 2017 in Free PCBs by DP | 18 Comments

BP-600x373

We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

(more…)

App note: How to measure thermal resistance of LED emitters and LED arrays

Posted on Sunday, June 18th, 2017 in app notes by DP | No Comments

an_lumileds_wp23

Another white paper from Lumileds about LED thermal resistance. Link here (PDF)

Thermal performance is the most critical factor of a well-designed LED lighting system. A lighting system with proper thermal design has higher efficacy, meaning more light can be extracted using less energy, and better long term reliability.

App note: Flash for “Selfies”

Posted on Sunday, June 18th, 2017 in app notes by DP | 1 Comment

an_lumileds_wp26

Effective front facing camera flash discussed in this white paper from Lumileds. Link here (PDF)

Smartphones are ubiquitous in everybody’s daily lives, a trend that shows no sign of slowing. A key component of the smartphone is the camera, which has gained market share over Digital Still Cameras due to its convenience.

As the demand for smartphone cameras increases, sensor makers are continuously working to improve the resolution and while 20MPix capability gained in importance for the main camera of the smartphone, the resolution race has begun for the front camera. With the rise in popularity of “selfies” and the 5 to 8 Mpix resolution for the front camera, it is not surprising that camera flash is starting to be more readily implemented for front cameras also. However, to make a successful front flash that captures an ideal “selfie,” there are certain illuminance requirements and shorter flash pulses that are recommended.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, June 16th, 2017 in Free PCBs by DP | No Comments

BP

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

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DIY robot design

Posted on Thursday, June 15th, 2017 in robotics, tools by DP | No Comments

robo-design2_853x234-min

A computational abstractions for interactive design of robotic devices by Ruta Desai, Ye Yuan and Stelian Coros from Carnegie Mellon University’s Robotics Institute:

We present a computational design system that allows novices and experts alike to easily create custom robotic devices. The core of our work consists of a design abstraction that models the way in which electromechanical components can be combined to form complex robotic systems. We use this abstraction to develop a visual design environment that enables an intuitive exploration of the space of robots that can be created using a given set of actuators, mounting brackets and 3d-printable components. Our computational system also provides support for design auto-completion operations, which further simplifies the task of creating robotic devices. Once robot designs are finished, they can be tested in physically simulated environments and iteratively improved until they meet the individual needs of their users.

Full details at cmu.edu.

Check out the video after the break. (more…)

Display Arduino analog input using LabVIEW

Posted on Tuesday, June 13th, 2017 in how-to by DP | 1 Comment

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Zx Lee shared detailed instructions of how to display the Arduino measurements using LabVIEW:

To get started, I will explain what is actually going on in Arduino. In this project, I am using an Arduino Nano to acquire signals and send the data to PC. As mentioned earlier, two analog input channels (A0 & A1) will be used to measure input signals. To ensure an accurate measurement is performed at fixed sample rate, the Arduino is configured to wait the predefined interval before taking a measurement and send to PC serially. The concept used is similar to the BlinkWithoutDelay example in Arduino. The benefit of using this method is that there is a while loop that always checks if it has crossed the desired interval. If it is reached, it will take the measurement, else it will skip and you can make it to work on other task.

More details at his blog here.

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, June 13th, 2017 in Free PCBs by DP | No Comments

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Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Raspberry Pi soft power controller – the circuit

Posted on Tuesday, June 13th, 2017 in R-Pi by DP | 5 Comments

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James Lewis has been working on a Raspberry Pi soft power controller, that is available on github:

The RetroPie project enables retro-gaming with a Raspberry Pi. All of the Pi models have enough computing power to emulate the major 8-bit and 16-bit computers of the 80s and 90s. With the Pi 3 I have even been able to play PS1 games with no problem. My current project is to put my Raspberry Pi running RetroPie into an old Super Famicom (SFC), or SNES, case. The catch? I want the original SPST power switch to work. And by work, I mean allow the Raspberry Pi to shutdown properly when the switch goes into the off position.  To accomplish this task, I am building a Raspberry Pi soft power controller.

More details at baldengineer.com.

Free PCB Sunday: Pick your PCB

Posted on Sunday, June 11th, 2017 in Free PCBs by DP | 26 Comments

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

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App note: DAC ICs: How many bits is enough?

Posted on Sunday, June 11th, 2017 in app notes by DP | 2 Comments

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A very old application notes from Analog Devices that tells about Nyquist Theorem, sampling rate and quantization used on DACs. Link here (PDF)

At the heart of every digital audio playback system lies the single-most critical component for high-fidelity audio: the digital-to-analog converter (DAC). These converters handle the delicate task of translating the 16-bit binary words encoded on the disc or tape into corresponding analog signals worthy of amplification and, ultimately, of the human ear.

App note: Influence of control loop by an output filter

Posted on Sunday, June 11th, 2017 in app notes by DP | 1 Comment

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Application note from Würth Elektronik about the effect of filters that are added to the output of switching regulators. Link here

The output voltage of switching regulators has a voltage ripple that can disturb with electrical power supplied circuits and lead to electromagnetic disturbances. Thus output filters are often used for noise suppression, which may under certain circumstances have an influence on the control loop. To prevent output power losses it may be necessary to compensate the control loop.

No matter what switching regulator topology is used, as a result of the parasitic series resistor ESR and the parasitic inductance ESL of the output capacitor, the output current causes an undesired residual ripple. Depending on the capacitor type selected, a relatively large residual ripple is created, which has varying wave forms. A common electrolytic capacitor, for example, can have a ripple voltage of up to a few hundred millivolt, depending on the output power of the switching regulator. If a ceramic capacitor is chosen, the ripple voltage may only be a few tenth of a Volt.

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