[CBMC]

Reading through tagents site I stumbled across the battery board for the PPA. I wanted to load 18 AAA batteries onto this board which is full capacity. My problem is with the power supply voltage. To charge these batteries do I need a 32v power supply? How do I get one of these?

 

[ITZBITZ]

http://www.tangentsoft.net/elec/teps/

Fairly easy to build, but anytime you deal with AC power, the standard warnings apply (i.e., danger).

 

[tangent]

Quote:

do I need a 32v power supply?

Yes, unless you only want a trickle charger.

 

[CBMC]

One more question. For the battery board it says the spacing is .400 mills(.100 mills larger than the PPA board). I was wondering if the Vishay/Dale RN60 line would fit? My second question involves the STEPS board. Will the RN60 line fit in those spots?

 

[tangent]

Quote:

I was wondering if the Vishay/Dale RN60 line would fit?

Possibly, but that isn't why the spacing is that wide. It's wide so you don't have to kink the leads so close to the resistor body. Since none of the small resistors (everything but R2) need to be more than 1/4W, I wouldn't use RN60s. It just makes it more difficult to stuff the board and it wastes money on the resistors.

Thinking more on it, the spacing between resistors probably doesn't allow for 1/2W resistors like the RN60s.

Quote:

Will the RN60 line fit in those spots?

The answer is virtually the same: use 1/4W unless you have a really good reason why not. There is one resistor I can think of on the STEPS that often needs to be 1/2W, and it has more space allotted to it than the others. Everything else should be 1/4W.

 

[ppl]

I Have used this Radio shack supply set to 30 Volts to Charge the battery Pack in my PPA and worrks great for 18 cells as it is unregulated and actualy puts out 36 volts at light loads. http://www.radioshack.com/product.as...Fid=273%2D1668

 

[ITZBITZ]

Hey ppl, that supply seems good for charging but since it uses a switch-mode supply, it probably wouldn't be so good for listening. Do linear regulators like the LM317 work with an upstream supply like that one? I'd wonder if the noise would cause problems in the regulator. Thoughts?

 

[tangent]

Quote:

it uses a switch-mode supply

No, it's unreglated, as ppl said.

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it probably wouldn't be so good for listening

Op-amps are good at rejecting 120Hz hum, and the PPA circuit has a lot of features to help reduce power rail ripple even more.

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Do linear regulators like the LM317 work with an upstream supply like that one?

Sure. All a linear-regulated supply is is an unregulated followed by a regulator. That's exactly what you're proposing.

Quote:

I'd wonder if the noise would cause problems in the regulator.

I'm sure you made that comment thinking about switching regulator noise, so I'll answer in that context. What would happen with the LM317 is that the regulator wouldn't remove much of the noise, because the regulator's noise rejection starts to rise after about 10kHz or so. By the time you get out to the hundreds of kHz or few MHz that most switchers run at, the regulator isn't doing much good at all.

This is where higher-performance regulators have their advantage.

 

[CBMC]

ppl, do you have a problem with heat running 18 cells? Is it in the same case as your ppl? Is yes, what case are you using? Sorry for all the questions just wondering.