# Tekin BC112C Power supply



## BrentP (Mar 1, 2002)

Hello all, I have a Tekin BC112C charger and would like to take advantage of the 12VDC 12 amp power source to run my lathe and break in motors. My question to all of you is, can I accomplish this, and if so how can I do it cheaply?

I run my lathe at around 4 volts and break in motors at around 3 volts.

Thanks to all in advance for your input.


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## BrentP (Mar 1, 2002)

Anyone, Nil, Dan the Man, Patcollins, any electrical engineers out there?


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## Dan the Man (Aug 21, 2002)

I'm not sure. I modded my BC67 to have a muffin fan; the results on how it worked were... unexpected. It doesn't help that I'm still not sure what I did, and I take no responsibility for the results if you try something akin.

Before the mod: Sitting on the bench, plugged in with no pack attached, it would register 20V on the LCD. Plug in a pack and it would register the pack voltage. Hit charge and the voltage would go up. All in all, just as you'd expect.

The mod: I opened up the case and spliced the leads for the fan (rated at 12V) in parallel with the circuit board where it attached to the rectifier.

After the mod: Sitting on the bench, plugged in with no pack attached, the voltage on the LCD registers at 16V and the fan runs fast. Hook up a battery, it registers the pack voltage and the fan runs fast. Start the charge, the fan speed takes a dive. Its input voltage takes a dive somehow. I'm still not sure why.

The charger continues to function; I think the amp meter might be off because of the fan, but it still peak detects just fine.

If you want a power supply to run whatever, I recommend getting a power supply. If you're frugal and handy you can try modding a PC supply, or you can just buy one off the shelf.


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## BrentP (Mar 1, 2002)

Thanks for the responce Dan. What I am after is really just a schematic design for a voltage reducer. The BC112C has wires with a plug that puts out a constant voltage of 12 volts 12 amps. I would like to build something that just plugs in to it and reduces the voltage to 3 or 4 volts whichever I need at the time. I am sure I would need a switch for the 2 different voltages.


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## patcollins (Sep 29, 2001)

The BC112C has a 24 volt ps in it not a 12V PS so be careful what you hook up to it.


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## BrentP (Mar 1, 2002)

My bad, Can this be done? And if so, How?


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## patcollins (Sep 29, 2001)

You could use a voltage regulator if you can find one that has the current capability. 

Here is how I did a fan on my charger, its a 6v fan and I use a 5V voltage regulator so the fan only sees 5 volts. 

http://home.earthlink.net/~pcollinsmsme/tekin1.jpg
http://home.earthlink.net/~pcollinsmsme/tekin2.jpg
http://home.earthlink.net/~pcollinsmsme/tekin3.jpg


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## BrentP (Mar 1, 2002)

Pat, where did you get your voltage regulator, and couldn't I just add some kind of resisters or diodes on the output side of the regulator to get the different voltages?


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## patcollins (Sep 29, 2001)

I got my voltage regulator at Radio Shack for $1.50, its only good for 1 amp though and you see I have a heat sink behind it $2. 

Yea you could use a resistor, diode, rheostat
Radio Shack also has a variable voltage regulator where you can adjust it via a pot, but again its limited to 1 amp. 

For comparison purposes a lathe motor can draw up to 10 amps, breaking in a stock motor can take up to 15 amps... my little fan uses 0.1 amps.


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## BrentP (Mar 1, 2002)

What about just a bunch of diodes in series? Would that acomplish what I am after? 

Thanks for all your help by the way, I really appreciate it.


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## patcollins (Sep 29, 2001)

Yes they will, each diode will cause a voltage drop of about 0.7 volts. You have to get a diode rated for the current that you expect to flow through it.


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## The Adjuster (Apr 1, 2002)

I have used 24v fans in different sizes if anyone is interested.


BrentP

Considering your voltage supply puts out 24 volts, and you want your output voltage to be about 3-4 volts, you would need about 30 diodes to accomplish what you want. If you are looking at a resistor set up, you will need resistors that will handle about 200 watts of power. That is some very serious power requirements.

Has anyone tried using a speed control as a switching regulator? The ESC would need to be able to handle 20 cells. You would just need to build the controller for it. I have seen schematics posted on different websites. It may be the least difficult for you to build.

Phil


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## BrentP (Mar 1, 2002)

Thanks everyone for the input. I guess I'll just keep using 2 & 3 cell packs.


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## EthanW (Mar 11, 2002)

*20 volt output*

Well I bought my tekin 112c so I could also hook up my other dc charger(gmvis commander) but come to find out it puts out 20 volts not the 12 I need is there any way to step this down or can I just hook up my charger to it an dit will work? 

Thanks,

ethan

PS I'd get a power supply but funds are a reason as well as space and weight in the pit bag.


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## patcollins (Sep 29, 2001)

Dont plug anything into except a Tekin charger that is ment to run off 24 volts or you will blow it up. 

You could get a DC/DC converter....but one that can provide the amperage you need will run you more than a power supply and it will be bigger. 

There really is no good efficient way of stepping it down to provide several amps. For very small ampdraws its pretty easy but for anything over 200 mA your basically out of luck.


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## EthanW (Mar 11, 2002)

*thanks pat*

why did they do this? It seems to be it if you design chargers to run off 12 volts you' d make your power supply 12 volts.


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## patcollins (Sep 29, 2001)

Couple of reasons, since someone buying the 112C might have more incentive to buy another Tekin charger. Electrically the higher voltage system is more efficient and allows you to charge packs with more cells (it allows 12 cell charging when run off 115V or 24V, but not 12 volts).


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## kcobra (Dec 3, 2002)

Very interesting thread. I would like to do something similar with a Rivergate 30amp power supply. Ideally I would like to have a little box I could put between the power supply and the device and be able to turn the voltage anywhere from 1v to 12v with a knob? Is this doable on the cheap? The cheapest RC product I know of that will do this is the Integy motor dyno (1v - 7v). It goes for about $100.

If the knob deal is no doable, I can do it with diodes wired in series, correct? Digikey has 30 amp, 30v schottky diodes for about $1.50 each. Will these work?


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