45 replies to this topic

[Mr. M]

My 1981 vintage power supply is fast fading and although it has been very loyal, it is time for a new one. I built the last one and am in the process of building the new one. If there is interest in seeing this, I will post pictures of the build. This is a bit different than the typical build here, so I am gauging if the forum would like to see this.

Chris McCarty

[Mach9]

Absolutely !

[Bill from NH]

I'm not currently in the market for another PS, but yes, I'd like to see what you're building.

[old & gray]

I built the last one and am in the process of building the new one. If there is interest in seeing this, I will post pictures of the build.

 

Yes I would like to see this. There is room and desire on this board for discussions of the electric part of our hobby.

[gotboostedvr6]

Better post very detailed pictures and step by step instructions or else!

[SlowBeas]

I'd also love to see your construction. Are you planning to build one that's reasonably small, or something that will power several demanding motors at once?

[Dushkwoneshe]

.

Would be very interested to follow along

with your build...

 

.

[Samiam]

Scratch building a power supply fits right in along with the chassis, motor, and body scratch building  threads.

 

Please go right ahead and thanks in advance for doing it.

[Mr. Hollywood]

yes please

[Mr. M]

Yes, this is reasonably small, but not compact form factor.
No, this is only a single motor supply.
Yes, this is what I would call a high power supply, around 10A max.
I plan to show the current supply that will be retired, it will provide some humor I think!
After all, it was 1981 when built.

[Mr. M]

This is the incumbent nearing retirement. It has done time in Centerville, Houston, Chicago, Cincinatti, Orlando, Kansas City, Detroit, and Clovis where it was drop kicked by the airlines and took 2 days to repair. The design is pretty simple, a variac in front of a transformer driving a 4 diode bridge with a hefty cap on the output of the bridge. There are AC plugs on the back for Dremel, soldering iron, and light. The case came from Radio Shack and everything else is surplus from Skycraft in Orlando. The whole supply probably cost $75. It would put out over 10A @ 15V all day. Now the connections are quite unreliable and the variac and transformer have internal shorts from airline abuse.

[Mr. M]

I built several of these for local racers, much cleaner looking fabrication than this one. Only known survivor is one with Terry Tawny who tells me it is still in use. They worked for everything from open, or Group 7 back in the day, motors to today's retro Hawks.

[Zippity]

I want to know how you get it to stick to the ceiling and why would you do that? 

[anarot]

Because they are on the opposite side of the world so therefore everything is upside down lol. The pictures are upside down. TM dose the same thing when I post pictures  using my new phone as well for some reason. 

[Zippity]

Ever thought that maybe you are holding your cell phone upside down when you are taking your photographs?

[Mr. M]

Nope, all is good, they are right side up. Greg?

[Zippity]

Chris,

 

I was just pulling your chain

[Mr. M]

I know, pulling it back...

[anarot]

Ever thought that maybe you are holding your cell phone upside down when you are taking your photographs?

Ummm. arn't you suppose to stand on your head when taking photo's lol. tried turning it around but TM still rotates them. 

[Zippity]

Don't blame TM for your inability to use a camera correctly

[Mr. M]

This is the new one. The front panel has analog volt and amp meters. I like analog because you can see variations for both at the same time and is more responsive than digital. To the right is the power switch, power on light, and fuse. Voltage control is the knob above the banana plugs. I like these plugs because you can either use a plug or tighten down on a wire.

The handles are mainly to protect the front panel along with providing a convenient carry.

The back has 120V AC plugs, power switch, AC fuse, and overall box fan. Eventually there will be a plug power on light on top of the case.

Most of the box and hardware are surplus from Skyscraft in Orlando or Frys Electronics. Wherever possible, I use industrial grade fixtures and hardware. The box is structural aluminum and was repurposed from a toll road controller.

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[Half Fast]

Chris you said the whole original unit cost around $75, but variacs weren't cheap then and are not cheap now. How did you do it?

 

Cheers

[Mr. M]

The answer is a good surplus place where they are used or new old stock. You can find them for about $20-25! Skycraft in Orlando, FL is amazing for stuff like this. Alternativly you can use a 100 W variable power resistor on the DC side, if you can find one. I have built them this way too.

[Mr. M]

If you want a new old stock variac, I have one left for $25 plus shipping that I would be glad to share.

[Mr. M]

The top view shows all the major components with the lid off. The front panel has the volt and amp meter on the left, filter cap behind it and the power switch, light, banana plugs on the right. The variable resistor is just above the banana plugs.

The big brick is a AC to DC regulated power supply,120V AC in, 12V DC @ 10A out. This is way overkill for this application, but again it was $20 at Skycraft in Orlando, FL. This is probably $150-200 new off the shelf. In the back you can see the AC plugs, fan on the left, and on the right the AC switch, fuse, and power on light.

The total cost is about $100. You can buy an off the shelf supply for not much more than this, but by building this I can have it the way I want it.

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