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jsteve126

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  1. Thanks hero999. Yes, it does look dangerous. I should say that the ac-dc motor drive part is not my design. I took this from an existing motor controller PCB that I have. It is all self contained, ie. just power cable and one pot for speed control. I want to add control from my PC. I am thinking of using a wireless serial connection. Do you think this would be safe enough? Getting back to the first question. You mentioned phase control on AC side. I've tried searching for info on this, but all I find are examples that use AC motors. Could you possibly point me in the right direction with an example link or two?
  2. I am currently trying to build a speed controller for a 90VDC motor. Please see the attached schematic. My question is; should GND and GNDB be connected directly or should there be some kind of isolation? I thought that a common GND would be necessary and bread-boarded it that way. It seemed to work; until I connected my microcontroller programmer, which is connected to my PC, which is earthed. This tripped my house's Earth Leakage Breaker. Result, no power in the house. Something obviously is not right, and I am hesitant to try this high voltage stuff again until I can get some help on it. Any advice would be greatly appreciated.
  3. Thanks for that audioguru. Well, it's done. Seems to be working perfectly. Here are some pics of the finished project. The top case is bolted to the large transformer on the bottom. The transformer inside the top case is for the 5V panel meter and fan board in the centre. This board uses an Atmega168 to read three LM35 sensors and control the two 12V fans via some MOSFETs. The heavy wire looks a bit over the top because this was initially a 15Amp project using a different board of course. Many thanks and regards to all in this thread.
  4. Just finished building my SPS. Can anyone point me to the page/s that talk about adjusting the trims and final testing procedures? A lot of pages to search through! Initial testing; I get full range of volts (0-30V) and can pull about 4A charging a 12V battery at 13.7V. Current limiting is working, but I haven't touched the trims. The 10W 0.47Ohm resistor gets very hot (about 60C). This is normal? Thanks
  5. Thanks for your response audioguru. It is appreciated. I'm surprised to learn that this, what I thought was quite a powerful transformer, is not that suitable. I have just measured the voltage with a 30,000uF cap across it and it was 35VDC. Does that sound about right for a transformer of this rating?
  6. I am going to try this project. I would like some advice about the transformer I intend to use. It is rated at 24V 400VA. Measuring the output, I get: 27.1VAC, rectified (no with caps) to 24VDC. Is this suitable for this project? Thanks
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