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LED traffic light

Posted on Wednesday, January 18th, 2017 in AVR, project logs by DP | No Comments

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Domen Ipavec shared his DIY LED traffic light in the project log forum:

Traffic lights are all around us, and they seem simple enough but are they really? Real traffic lights can be a very complicated system because it requires sophisticated control and coordination for smooth and safe traffic.
The traffic light I made is much simpler. My sister works in a kindergarten where kids needed a simple traffic light for when they are riding their bikes on the playground.
The traffic light uses some cheap LEDs from China, a step-up converter and an Atmel attiny841 microcontroller to change the light from red to green at a programmed interval.

More info at Domen Ipavec’s blog.

Via the forum.

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

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, January 17th, 2017 in Free PCBs by DP | 1 Comment

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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.

A 400W (1kW Peak) 100A electronic load using linear MOSFETs

Posted on Monday, January 16th, 2017 in DIY by DP | No Comments

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Kerry Wong built a 400W/100A electronic load using linear MOSFETs:

 I bought a couple of IXYS linear MOSFETs (IXTK90N25L2) a while ago to test their capabilities when used as electronic load, and the result was quite impressive. So I decided to build another electronic load using both MOSFETs. As you can see in the video towards the end, this electronic load can sink more than 100 Amps of current while dissipating more than 400W continuously and can withstand more than 1kW of power dissipation in pulsed operation mode.

More details at Kerry Wong’s blog.

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

Shirt Pocket Transceiver with the Si5351 and OLED

Posted on Monday, January 16th, 2017 in RF by DP | No Comments

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Pete Juliano’s (N6QW) Shirt Pocket Transceiver with the Si5351 and OLED display:

In 2011 I fulfilled a dream of building a shirt pocket sized QRP SSB transceiver. Well actually I built two of them and the second was a diminutive 2″ X 4″ X 2″. Both used through hole components –so no cheating with SMD. In each case the IF was 4.0152 MHz and employed a crystal switched VXO that essentially gave about 100 kHz on 20M SSB. But it was a VXO and there was not full band coverage. But nevertheless a small miracle (or so I thought) that they both worked! You can see the two versions blow.
But with new technology now available to us my next goal is to fit the larger rig with the Si5351 and an OLED display. Today I made that happen!

Project info at Pete N6QW’s blog.

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

Free PCB Sunday: Pick your PCB

Posted on Sunday, January 15th, 2017 in Free PCBs by DP | 18 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:

(more…)

App note: Operation evaluation of ultra low ON resistance MOSFET supporting quick charge for 1 cell Lithium ion battery protection

Posted on Sunday, January 15th, 2017 in app notes by DP | No Comments

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ON semiconductor’s application note on faster charging of Lithium Ion batteries with consideration on heat suppression. Link here (PDF)

Currently, because LiB (Lithium Ion Battery) is superior in current density and electromotive force, it becomes mainstream of batteries for mobiles such as smart phone. However, because LiB is weak at over-charge and over-discharge, a control circuit is necessary to be used in combination with LiB. For the purpose of LiB current control, MOSFET is used.

This time, we would like to consider the operation and heat transfer of the CSP (Chip Scale Package) product, which is used for current control, with very small size and ultra-low ON resistance.

App note: Application precautions: Power MOSFET application notes

Posted on Sunday, January 15th, 2017 in app notes by DP | No Comments

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Toshiba’s application note on the things to consider when picking a power MOSFET. Link here (PDF)

This document explains selecting MOSFETs and what we have to consider for designing MOSFET circuit, such as temperature characteristics, effects of wire inductance, parasitic oscillations, avalanche ruggedness, and snubber circuit.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, January 13th, 2017 in Free PCBs by DP | No Comments

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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…)

Building an AT2XTKB (AT to XT) keyboard adapter on prototype board

Posted on Thursday, January 12th, 2017 in DIY by DP | No Comments

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Matt built an AT2XT keyboard adapter on prototype board using an AT to PS/2 keyboard cable.

Project info at Matt’s Tech Pages.

Sony TC-252 reel to reel player restoration

Posted on Thursday, January 12th, 2017 in repair by DP | No Comments

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Dilshan Jayakody has written an article about Sony TC-252 reel to reel player repair:

As a first step of the restoration we remove the LA4440 module attached into that recorder and rewire the player with original wiring layouts. After rewiring we check all the transistors in that player and find-out that the couple of 2SC634 transistors are damaged in that player. Because 2SC634 is not available in the market we replace those damaged transistors with BC548 transistors.
For the front panel potentiometers we use standard 10K and 20K (log) potentiometers available in the market.
To fix motor speed problems we replace 1.5MFD + 0.5MFD multi-section can capacitor with two separate 1.5MFD and 0.5MFD (450V) AC fan capacitors.

More details at Dilshan Jayakody’s blog.

Inside the 74181 ALU chip: die photos and reverse engineering

Posted on Wednesday, January 11th, 2017 in reversed by DP | No Comments

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A detailed die photos and reverse engineering of the 74181 ALU chip by Ken Shirriff:

What’s inside a TTL chip? To find out, I opened up a 74181 ALU chip, took high-resolution die photos, and reverse-engineered the chip.1 Inside I found several types of gates, implemented with interesting circuitry and unusual transistors. The 74181 was a popular chip in the 1970s used to perform calculations in the arithmetic-logic unit (ALU) of minicomputers. It is a moderately complex chip containing about 67 gates and 170 transistors3, implemented using fast and popular TTL (transistor-transistor logic) circuitry.

More details at Ken Shirriff’s blog.

Printed Circuit Board V-Groove cutting machine

Posted on Wednesday, January 11th, 2017 in PCBs by DP | No Comments

This is how V-Grooves are cut into PCBs. V-Grooves are half-cuts into the PCBs that allow them to be snapped apart easily. Minimum V-Groove cut length in generally 8cm due to machine cutting length. V-Grooves must be cut across the entire PCB length, it is not possible to make short internal cuts.

This is from our PCB documentation at DirtyPCBs.com about check it out for more PCB manufacturing details.

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, January 10th, 2017 in Free PCBs by DP | No Comments

IRToy-600x369

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.

Tear down of a super capacitor

Posted on Tuesday, January 10th, 2017 in Teardowns by DP | No Comments

A teardown video of a 1 Farad super capacitor from Electronupdate:

In a recent video on the tear down of an electrolytic cap a viewer was wondering what a super capacitor looks like.
They have much more capacitance: 10,000 time more on average for the same volume.
Surely this means the physical construction must be amazing! Interestingly enough, the construction is almost identical.. the secret is in the dielectric.

More details at Electronupdate blog.

EasyESP-1: a rapid prototyping and development board for ESP8266

Posted on Tuesday, January 10th, 2017 in dev boards, wireless by DP | No Comments

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Raj over at Embedded Lab has designed a development board for ESP8266:

EasyESP-1 is a rapid prototyping board for the low-cost, WiFi-enabled ESP8266 microcontroller. With an onboard USB-to-Serial converter pre-installed, EasyESP-1 does not require any additional hardware to download your application firmware to the ESP8266 chip. The ESP module used in this development board is ESP-12E. All the I/O pins are broken out to 0.1” female headers for easy access, as well as to standard Grove connectors for connecting Grove sensors and other compatible modules. The 180-point breadboard further facilitates experimenting and testing of external circuits.

List of features

  • Easy access to all GPIO pin through female headers and Grove connectors
  • On-board USB-UART chip for easy programming and debugging
  • 180-point breadboard for experimenting with test circuits
  • On-board 3.3V (800 mA) regulated power supply
  • Two tact switches for user inputs, and one output LED
  • Slide switch to enable/disable auto Wake Up feature during Sleep mode

Full details at Embedded Lab blog. It’s also up on Tindie.

Curtis 1231C-8601 500A PWM DC motor controller teardown

Posted on Monday, January 9th, 2017 in Teardowns by DP | No Comments

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Jay did a teardown of a Curtis 1231C-8601 500A PWM DC motor controller:

The Curtis 1231c-8601 power board is relatively simple. It uses 18 MOSFETS in parallel to switch current from the motor- terminal back to the battery- terminal (the motor+ lead is already connected to battery+). The MOSFETs it uses are IXYS IXTH50N20 SP9536 chips. The center lead is bent up over the chip and soldered to a ring terminal, such that the screw that attaches the chip to the heat sink also electrically connects that pin to the heat sink.  Most chips that attach to a heatsink have a metal back, but the IXTH50N20’s used here do not, so it appears that they had to take extra assembly steps to electrically couple it to the heatsink.

More details at Jay’s blog.

App note: Redefining a new state-of-the-art in microampere current-sense amplifiers

Posted on Sunday, January 8th, 2017 in app notes by DP | 1 Comment

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Silicon Lab’s TS1100 and TS1101 current sense amplifier’s features discussed in this app note. Link here (PDF)

Sensing and controlling supply current flow are a fundamental requirement in most all electronic systems from battery-operated, portable equipment to mobile or fixed-platform power management and dc motor control. High-side current-sense amplifiers (or “CSAs”) are useful in these applications especially where power consumption is an important design parameter. New CSA developments offer even greater benefits in allowing engineers to save power without sacrificing performance.

Free PCB Sunday: Pick your PCB

Posted on Sunday, January 8th, 2017 in Free PCBs by DP | 30 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: Multiple Capture/Compare/PWM (MCCP): Extending the functionality for low-cost motor control applications

Posted on Sunday, January 8th, 2017 in app notes by DP | No Comments

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Microchip’s MCCP module on PIC32 devices demonstrate the built-in majority detection filter for simpler motor control drives. Link here (PDF)

The motor control industry has been focusing on designing low-cost motor control drives for various applications. The consumer demand for low-cost motor control applications is driving this trend.

Microchip has recently introduced the PIC32MM family of microcontrollers, which is capable of addressing the low-cost motor control requirements. The low-cost solution benefits from the capability of the Multiple Capture/Compare/PWM (MCCP) module available in Microchip’s PIC32MM controllers. This document
illustrates the usage of the MCCP module in the PIC32MM0064GPL036 controller, from Microchip Technology, to deliver a development platform for motor drive applications.

MCCP implementation, similar to the motor control solution discussed in this document, can also be extended to Microchip’s PIC24 and dsPIC33 family of devices which feature MCCP.

Qume 842 8″ floppy drive with a RC2014 Z80 retrocomputer

Posted on Saturday, January 7th, 2017 in hacks by DP | No Comments

Dr. Scott Baker writes, “In this video, I try out some Qume 8 inch floppy drives that I bought on eBay. I interface them to a WD37C65 controller on my Z80 CP/M computer and I format the disks and read/write some files to them.”

More details at Dr. Scott M. Baker’s blog.

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