a "Greener" Class A - Peltier as CCS?

[john65b]

Please don't hurt me if a dumb idea...but why not?

I was looking at building a Zen-lite and thought why not a current hogging Peltier and get some real use out of those amps?

Easy on me. I am relatively new and thenthitive.

Also forgive me if this has been discussed elsewhere - I did search...

[tschrama]

You mean using a Peltier as a CCS? to bias the gain stage output transistor?

[john65b]

Yes. Crazy?

[tschrama]

no, not crazy, from what I understand is that a Peltier ellement is resistive in nature.. or isn't it?

An amplifier output stage biased by a resistor will be very low in effecienty. I did found a Peltier ellement haveing a Imax of 3.9A and a Umax of 15Volt, so that might be suitable.

If the transistor is attached to the Peltier ellement, the wil beistor cooler. The 'hot' side of the peltier can be attached to a smaller heatsink. The total energy dissipated in heat will not degrease, but since the heatsink can be hotter, is can be smaller.

grtz,
Thijs

[john65b]

Exactly. The otherwise "wasted" power can be at least used to cool the outpt devices...methinks...

I wanna try, but in the middle of finishing off my basement...

[Maousse]

Hi folks,

Green is not the right term, as Peltier devices have very poor efficiency, the total power consumption would be quite a fair amount higher.

If the idea is to use the Peltier effect plates as CSS, it's really not the right use. Peltier are not CSS, the current is voltage dependent and not in a linear way. To make it short, Peltier effect devices are PN diodes.

BTW, FETs sound good at higher than ambiant temperature, if I'm not mistaken.

My 2 cents

[tschrama]

Hi,


'Peltier effect devices are PN diodes.' Are you sure about this? I downloaded a datasheet from a peltier ellement from Farnell, and it looks like a linear resistive device to me... Marlow-Industries type RC12-2.5

If it really is a PN ellement, what is the voltage drop? maybe it's even more suitable as part of a CCS?

anyways... I also find the term 'green' misleading, as the exact same energy is dissipated, not less. The current to make a peltier ellement work, is the same current to bias the output resistor, so no extra enegy is disspated.

The peltier ellement as a output-stage current source, wil enbale to move the heat from the output transisot to the heatsink more effeciently, that's the advantage.

[jackinnj]

If you put a block of dry ice on one side of your peltier device and allow the other side at room temperature, you can derive power to run your amplifier (they are thermogenerative).

[john65b]

OK, "Green" was not the correct term. Same energy generated - but some of the energy dissipated is better utilized to decrease sink size?

The thermogenerative nature of the device is interesting. The bigger the delta T, the more amps produced. A chunk of dry ice on one side and the output device on the other would provide enough VA drive the amp...maybe a pipe dream, but kind of interesting nontheless...

More realistically, the peltier could be used between the device and the room temp sink to generate 15 vdc to power for a preamp circuit or input section of an amplifier. I guess this could better qualify it as "Green"?

Using the Peltier would allow the use of a smaller heatsink...and the heatsink could be run much hotter (it is the exhaust heat of the peltier and device) Ultimately the heatsink would no longer have to be connected to the output devices being cooled...and maybe running an output device harder - to 75w limit? Wouldn't it be nice to have an aleph 60 with a single pair of output devices in a small chassis?

If the pair of devices were able to be kept consistently below 60C, why not? I know other SOA limits would possibly be breached, but temperature would be the biggest limitation?

[flacoman]

Cool your beverage and groove your tunes at the same time!
Built a couple of mini fridges with peltiers and want to do my car's cupholders.
Regards
Jorge