Categories

Free PCB Sunday: Pick your PCB

Posted on Sunday, September 17th, 2017 in Free PCBs by DP | 23 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: Using trench technology MOSFETs in hot swap applications

Posted on Sunday, September 17th, 2017 in app notes by DP | No Comments

an_irf_an-1211

Safely use trench MOSFETs on hot swap application by determining its operation within its SOA in a limited time, app note from International Rectifier. Link here (PDF)

Hot Swap circuits are used to allow for “Hot Plugging” of circuit boards into back planes. The applications that require such functionality are mission critical, such as servers and communications equipment that must operate continuously. These circuit boards are usually employed in a rack mount system which consists of an array of boards that cannot be powered down. Thus hot swapping allows for a bad board in the array to be replaced without powering down the entire system.

In essence the Hot Swap circuit, which is between the board input rail and the rest of the board’s circuitry, is an inrush current limiter that allows for charging of the bulk capacitance in a controlled manner. Also faults, such as over current and overvoltage are managed by Hot Swap circuits.

App note: Class D audio amplifier performance relationship to MOSFET parameters

Posted on Sunday, September 17th, 2017 in app notes by DP | No Comments

an_irf_an-1070

Application note from International Rectifier on MOSFET paremeters to consider when designing a Class D audio amplifier. Link here (PDF)

Class D audio amplifier is a switching amplifier that consists in a pulse width modulator (with switching frequency in order of several hundred kHz), a power bridge circuit and a low pass filter. This type of amplifier has demonstrated to have a very good performance. These include power efficiencies over 90%, THD under 0.01%, and low EMI noise levels that can be achieved with a good amplifier design.

Key factors to achieve high performance levels in the amplifier are the switches in power bridge circuit. Power losses, delay times, and voltage and current transient spikes should be minimized as much as possible in these switches in order to improve amplifier performance. Therefore, switches with low voltage drop, fast on and off switching times and low parasitic inductance are needed in this amplifier.

MOSFET have proved to be the best switch option for this amplifier because of its switching speed. It is a majority carrier device, its switching times are faster in comparison with other devices such as IGBT or BJT, resulting in better amplifier efficiency and linearity.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, September 15th, 2017 in Free PCBs by DP | 1 Comment

irtoyv3-600x369

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…)

Network cable tester

Posted on Friday, September 15th, 2017 in DIY by DP | 4 Comments

picture-IMG_20170910_210643-600

Dilshan Jayakody writes, “This is an automatic Cat6 / Cat5 network cable tester designed using NE555 timer and 4017 decade counters. This unit test all 8 wire lines of twisted pair network cable and indicate pass/fail status with single LED. We design this unit to test network connectivity issues in Cat6 / Cat5 cable systems and it is capable to check both crossover and straight-through type network cables.”

More info on his blog here.

DIY ISA game control adapter with parallel IO

Posted on Tuesday, September 12th, 2017 in DIY by DP | No Comments

picture-isa-gca-io-board-600

Dr. Scott Baker has published a new build:

My Xi 8088 homebuilt PC is running a little short on slots, so I wanted to combine the functions of a game control adapter and an 8255 PIO board. Two functions in one slot. As to why one wants each of these things:

  • A game control adapter is used to interface to PC joysticks. These are the old-style analog joysticks with the 15-pin connectors.
  • An 8255 board is a general purpose interfacing board, providing 24 bits of digital IO that can be configured as inputs, outputs, or a mix of both. This is not in and of itself a “parallel port”, but could probably be used to implement one.

See the full post on his blog.

Building a high capacity battery bank

Posted on Tuesday, September 12th, 2017 in DIY by DP | No Comments

Kerry Wong has been working on building a high capacity battery bank using his DIY tab welder.

More info on his blog here.

Free PCB Sunday: Pick your PCB

Posted on Sunday, September 10th, 2017 in Free PCBs by DP | 19 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: 12Vac LED Driving without smoothing capacitors

Posted on Sunday, September 10th, 2017 in app notes by DP | 1 Comment

an_diodes_an56

Application note from Diodes Incorporated on driving 12Vac LED without smoothing capacitors with their Zetex ZXLD1360 LED driver IC and SBR2A40P1 super barrier rectifier. Link here (PDF)

LED based architectural lighting is now coming of age, but there are still some problems to be considered when designing luminaires to be fitted into existing installations.

This Application Note discusses some of the challenges and shows that the omission of the traditional smoothing capacitors has advantages in saving cost, space and PFC problems.

App note: CAN Bus – Common high speed physical layer problems

Posted on Sunday, September 10th, 2017 in app notes by DP | No Comments

an_vector_AN_ANI_1-115

App note from Vector on three commonly encountered high speed CAN physical layer problems – bus termination, signal levels, and ground. Link here (PDF)

Determining the exact cause of a CAN problem is not at all simple.

Is the problem in hardware or software? Is the problem on the circuit board or on the CAN network wiring?
Sometimes the problem may not be at the module level – perhaps the cause is up at the system level.

This application note discusses methods used to investigate serveral of the more common CAN Physical Layer problems typically encountered when debugging high-speed CAN.

The Boat PC – a marine based Raspberry Pi project

Posted on Friday, September 8th, 2017 in DIY, R-Pi by DP | 2 Comments

picture-complete_rear-600

Domipheus has published a new build:

In late 2015 I was doing my usual head-scratching about what gifts to get various family members for the holiday season. My wife mentioned making something electronic for my father-in-laws boat, and after a few hours of collecting thoughts came up with an idea:

  • A Raspberry Pi computer, which could be powered off the boats 12v batteries
  • This computer would have sensors which made sense on a boat. Certainly GPS
  • I’d have some software which collated the sensor data and displayed it nicely
  • This could plug into the onboard TV using HDMI
  • It would all be put into a suitable enclosure

Project info at Domipheus Labs homepage.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, September 8th, 2017 in Free PCBs by DP | No Comments

irtoyv3-600x369

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…)

Teardown and experiments with a Doppler microwave transceiver

Posted on Thursday, September 7th, 2017 in Teardowns by DP | No Comments

picture-xbandtransceiver-600

Kerry Wong did a teardown of Microsemi’s C900502 X-band planar transceiver:

I got a couple of Microsemi’s C900502 10.525 GHz X-band Doppler radar motion sensors a while ago. This batch was made in UK and had “UK patents 2243495 and/or 2253108 apply” printed on the case. I have seen a teardown of an HB100 Doppler radar module before and was wondering if I this one is any different inside.

See the full post on his blog.

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

Free PCB Sunday: Pick your PCB

Posted on Sunday, September 3rd, 2017 in Free PCBs by DP | 32 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: Through-Hole versus SMD components

Posted on Sunday, September 3rd, 2017 in app notes by DP | 1 Comment

App note from Vishay on the advantages of using Through-Hole mounting. Link here (PDF)

Most electronic gadgets are designed to interface with humans, and we humans are very abusive to most electronic devices. We drop them, poke them, open and close them, and in general feed stuff into and out of them.

It is well understood that a through-hole connection to the PCB is mechanically stronger than most surface-mount connections. By comparison, the strength of the bond that holds a surface-mount component to the PCB is limited to the strength of the solder joint that holds it to the surface of the laminate. As parts get smaller, so does the amount of solder and thus the strength of the bond.

App note: Thermal management in surface-mounted resistor applications

Posted on Sunday, September 3rd, 2017 in app notes by DP | No Comments

an_vishay_tmismra

App note from Vishay on PCB thermal management specifically on components like SMD resistors, where if allowed a design change (e.g. change in SMD size or change in more heat tolarant ones) must be implemented in order to squeeze more thermal capability. Link here (PDF)

Thermal management is becoming more important as the density of electronic components in modern printed circuit boards (PCBs), as well as the applied power, continues to increase. Both factors lead to higher temperatures of individual components and of the entire assembly. However, every electrical component in an assembly has to be used within its prescribed operating temperature limits due to its material properties and reliability aspects. In this application note, experimental results are provided in order to prevent overheating of electronic devices such as surface-mount resistors.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, September 1st, 2017 in Free PCBs by DP | 2 Comments

irtoyv3-600x369

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…)

Bus Pirate v3.8 free PCB build

Posted on Thursday, August 31st, 2017 in builds, Bus Pirate by DP | No Comments

pDIiyIP_WAAAV9PM

@ramin_rajabi tweeted picture of his free Bus Pirate v3.8 PCB build. The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Precision voltage source – voltage calibrator

Posted on Thursday, August 31st, 2017 in DIY by DP | 3 Comments

picture-blockdiagram-600

Mare writes, “What I missed in my workshop is nifty small programmable precision voltage source which can be used as calibration voltage source for testing and calibration purposes. I decided to make one, because instruments which have word “calibrator” have price with same digits as there is vocals in this magic word.”

More details at Mare & Gal Electronics.

Teardown of a Philips dimmable LED bulb

Posted on Thursday, August 31st, 2017 in Teardowns by DP | 2 Comments

philipsLED-600

Kerry Wong did a teardown of a Philips dimmable LED bulb:

One of the first things you will notice about this light bulb is that the compact construction. Most noticeably the lack of the telltale heatsink fins. As a result however, the heat dissipation capability is greatly sacrificed. During normal operation when mounted pointing downwards without any airflow obstruction, the case temperature raised to above 60°C within a few minutes. I could only imagine what the temperature would be like when the light bulb is mounted facing upwards in a semi-enclosed light fixture.
So I decided to take it apart to see the what the construction looks like inside.

See the full post on his blog.

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

Next Page »

Recent Comments

  • Noy: Yuuup
  • KH: I guess this is a failed attempt at making a pass/fail cable tester out of discrete ICs. A single pass/fail LED is not that useful....
  • Max: Considering it only seems to test that all wires conduct, I'm not sure what exactly does this show you that 7 LEDs each powered through...
  • David: Please
  • Dan: Such comment. Wow.