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Anyone have a schematic for a 12volt 20amp PS?

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joecool85

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Well? I'd like to build one for my gfs dad. He keeps blowing cheap ones. He runs a cab stand and uses a PS for his base station radio.
 
If your a beginer you better go by putting lots of TO-3 transistors on a HUGE fan cooled heatsink.

If you know somthing alredy you better make an switchmode PSU.Wich is much smaller but also more complicated.
 
joecool85 said:
Well? I'd like to build one for my gfs dad. He keeps blowing cheap ones. He runs a cab stand and uses a PS for his base station radio.

WOW.. Yea, a switcher for sure.

Another option, a GEL 12V battery (gold cart ones are cheap) and a charger (deep cycle) , and when he is off work, it is charging, and when working, it charges and has the power he needs.

When I said GEL, I mean sealed battery so there are no major gases that can cause a problem. Also, if there is a power outage, he is still in business with his station (in the dark hehehe)
 
There are several power supply projects described in various editions of the ARRL Handbook for Radio Amateurs. One is a switcher for up to 40 amps.

Building one certainly is a way to do it however you might first try to look closely at the situation to be sure you size things up correctly. Things I'd wonder about:

1. Has he got the PS packed in where there is no ventilation. If he does that to one you build it might not last any longer.

2. Is the PS he is using rated for the duty cycles he imposes on it - relatively constant seems likely in this case. Again, you need to build yours to suit. Be careful. Not all homebrew designs are done with commercial service in mind. Many power supplies sold for home use are probably not built with the constant use that a commercial supply might.

After you've sized things up have a look at power supplies that are made for the application. See what they cost and what kind of warranties they have, etc. Then compare that to the cost and effort required by you and see where you come out.

On the battery side I'll share what I've done already and what I will be doing for my ham radio (100 watt). My RV has an electrical system that is mostly 12 vdc. An traditional "convertor" consisted of a transformer, rectifier and control board that provided rough dc and some filtered dc as well as a small amount to charge the battery. On failure of AC or just by choice the control board would switch everything on to the battery. It wasn't a great system. I removed all that stuff and put in an SMPS made for that application. It's output is paralleled with the battery so that everything is on-line across the battery at all times. The SMPS voltage is adjusted to suit the battery and deliver the power needed to circuits in the RV - up to 45 amps. The great thing is that this thing keeps chugging at 60 vac with some drop off in amps but it still works. It also has desulfation cycles so that the battery is maintained. On power dips or during thunderstorms there isn't a hint of any disturbance - which normally takes the control system for refrigerators off line for everyone else. Mine just keeps going. I power my ham radio station from it and unplug the AC to participate in emergency power contests.

I'd duplicate this at home. The advantage is that should a power failure be longer term charging the battery would be faster that it might be otherwise and would be bump free. Put a generator on-line, plug in and you've got 45, 60, 75 or whatever amps you want.

Sorry for the long note but thought you might benefit.
 
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