Projects Quick Update March 1st 2017

Updated board for Dual channel DC Load
Updated MOSFET board for Dual chan­nel DC Load Version 0.2

Quick Projects Update

Way too many projects and too lit­tle time. Luckily I had a few days off from work to make a bit of progress on sev­er­al exist­ing projects, and to start some new ones.

I designed a new Linear MOSFET board for the DC Load project. Now ver­sion 0.2 with dual MOSFETS and dual 0.5 ohm pow­er resis­tors. The orig­i­nal sin­gle MOSFET ver­sion did meet all the require­ments, but at high­er loads I was not able to trans­fer enough heat thru the sin­gle pack­age to the heatsink with­out exceed­ing my set­point for junc­tion tem­per­a­ture. I also com­pro­mised on the max­i­mum load spec­i­fi­ca­tions for the con­tin­u­ous duty cur­rent and volt­age. Also by chang­ing the max load spec­i­fi­ca­tion to 18 Volts at 10 Amps, I was able to increase the cur­rent sense resis­tor from 0.005 to 0.01 ohm which will improve the res­o­lu­tion at all cur­rent ranges.

Dual Linear MOSFET DC-Load assembly with power devices installed
Dual Linear MOSFET DC-Load assem­bly with pow­er devices installed

Next step in the project is devel­op­ing a 4 wire PWM fan con­troller and heatsink tem­per­a­ture mon­i­tor­ing using the Teensy 3.2 board.

Dual Linear MOSFET DC-Load V 0.2 assembly bottom view
Dual Linear MOSFET DC-Load V 0.2 assem­bly bot­tom view

Progress on the Quad Voltage Reference ver­sion 2 tem­per­a­ture con­trolled envi­ron­ment for improved sta­bil­i­ty. I still need to fin­ish the pro­gram­ing of the ATTiny85 proces­sor and imple­ment­ing a PID con­trol.

Quad Voltage Reference V 2 insulation for temperature controlled environment.

Quad Voltage Reference V 2 insu­la­tion for tem­per­a­ture con­trolled envi­ron­ment.

Quad Voltage Reference V 2 full oven insulation
Quad Voltage Reference V 2 full oven insu­la­tion

New series of projects for SDR (Software Defined Radio) recep­tion of ADS‑B air­craft, and AIS marine ship data recep­tion, along with some test boards for mount­ing volt­age ref­er­ence IC’s.

Low Noise Amplifier and filter board prototype for SDR radio
Low Noise Amplifier and fil­ter board pro­to­type for SDR radio
Testing LNA + Filter board with a Nooelec NeSDR Smart module
Testing LNA + Filter board with a Nooelec NeSDR Smart mod­ule
Voltage reference prototype isolation board
Voltage ref­er­ence pro­to­type iso­la­tion board

3 Replies to “Projects Quick Update March 1st 2017”

  1. I can’t help but notice that the cur­rent sense resis­tors pic­tured in the DC load project are 0.5 ohm, but you men­tion that the change was from .005 ohm to .01 ohm. Can you elab­o­rate? Also, can you advise the item num­bers for the clips that attach the TO-XXX pack­age devices to the heat sink? Many thanks!

    1. Hi Sonny,
      The two 0.5 ohm heatsink mount­ed resis­tors are not the sense resis­tor, the 0.01 ohm 4 wire sense resis­tor mounts just below U1 on the cir­cuit board. The 0.5 ohm resis­tors are for addi­tion­al load dis­si­pa­tion and to assist in bal­anc­ing the cur­rent across both L2 MOSFETS. The clips are Wakefield-Vette OMNI-UC for the TO-247 MOSFETS, and OMNI-220C for the TO-220 resis­tors.

      Greg

  2. Greg: Thanks so much for the info.! Sorry I am just get­ting around to see­ing your reply. I am going to have to order a cou­ple of your V2 boards. I just saw your 1090 MHz LNA/Filter project and that one looks fun too.

    Thanks again!

    Sonny

Leave a Reply

Your email address will not be published. Required fields are marked *