# 2 Transistor Step Up Circuit



## **DONOTDELETE** (Apr 29, 2001)

Hi Satcure fans,

For all those fans of the Satcure circuit, here I believe, is the 2 transistor step-up circuit mentioned on the Satcure Bead thread.

I hope someone will look it over and try it. I don't have all the parts in my junkbox and I'm not sure right now what transistor would make a good substitute for the one originally used. It looks like a pretty easy circuit to breadboard and test though. 
http://dustbin.virtualave.net/circuits/led1v5.html 

Have fun,

Mark


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## Steelwolf (Apr 29, 2001)

Thanks for looking this up mooremj, but pardon me. The circuit you pointed out uses 3 transistors and looks very complex. THis may not be what Gadget was talking about. In addition, I believe what we were looking for in the 2 transistor circuit was that it used capacitors rather than inductors to deliver the higher voltage. This one still uses a coil. But the circuit you pointed out looks interesting enough that I would definitely try it. And it looks as though we can modify the circuit to use a capacitor instead of an inductor. (Why am I obsessed with using a capacitor??)


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## **DONOTDELETE** (Apr 29, 2001)

Hello Steelwolf,

In looking the circuit over more carefully I see that there are in fact 3 transistors. This was the circuit that rang a bell when Gadget mentioned a two transistor circuit. In my haste I didn't even notice the third transistor. I'm glad I didn't try to build it with that particular oversight.



It still doesn't look that hard to assemble on a breadboard though. I sure hope you'll try it out and let us know how it works out What transistor will you use? I see all three are the same.

Maybe you're obsessed with using a capacitor because you hate coils as much as I do now after building the Satcure circuit!





Thanks for pointing out my little error





Mark


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## papasan (Apr 29, 2001)

here's a good one i've been following for a bit, guy is supposedly on vacation so he hasn't really followed through...apparently the IC he used is no longer in production...nice and small and he's even made a board for it...

http://communities.msn.com/whitelightLED/discussion s.msnw?action=get_message&ID_Message=56&LastModified=4675319196790811505


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## Steelwolf (Apr 30, 2001)

mooremj, the circuit you described uses 2 PNP transistors and 1 NPN. The unit numbers are BC546 and BC556. They are not the same transistors. 

The guy did mention that PNP transistors have very little voltage drop across them. I wonder if that holds true for NPN transistors, and if not, will it be worthwhile to modify the SatCure circuit to use a PNP transistor instead?

Anyway, I think why I hate coils is because, so far, I've had to wind everyone of them myself and they are fiddly creatures to wind. I'm not sure of the inductive capacity of the coil and the wires are thin and rather fragile. 

Anyways, when time permits I'll head down to **** Smith's and try to find the components. Can't cost more than $5 total. 

papasan, the circuit you describe uses a hard to find IC chip. In a way, it is similar to the circuit I describe in the other thread. That other circuit uses the Texas Instruments TL496 chip. Both the chips are, apparantly, obsolete, out of production and generally hard to find. The only apparant advantage of the TL496 chip is that you don't need that resistor which the MAX778 chip requires.

Anyways, I wonder what chips have been built to replace these "obsolete" chips and whether there is a schematic to explain how to use them.


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## **DONOTDELETE** (Apr 30, 2001)

OK, that does it. I've got to stop trying to read printed schematics by the light of my computer monitor during during those 3 minute TV commercial breaks.



It probably wouldn't hurt to get a magnifying glass too. 

Mark


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## Go Go Gadget Flashlight (May 3, 2001)

Lol guys! Yeah, these aren't the 2 trans. cct I'm working on. One of the members here (Dave) sent me a small PCB out of a solar walkway light.

It uses 2 transistors, one PNP and one NPN, an inductor, a couple caps, and a couple resistors.

I'm still dissecting it and working on its schematic. Once I get that, I'll build it on a breadboard and see what it's capable of.

I still have to add the values, but here's the schematic... I think. Won't know till I build it.





I'm done with finals now, so I should have a little more time for "research".


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## Marked (May 6, 2001)

How about some one drawing up the circuit in the Brinkmann light.


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## Go Go Gadget Flashlight (May 6, 2001)

I have that here somewhere. My bet is that it's very similar to this solar light's cct.

I'll see if I can find it again...


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