Temperature Monitoring in Leach Amp

[wrl]

Ok, heres the deal. I just finished getting my system working nicely. (Leach amp, Bass Amp, Active Crossover, Hybrid ESL's) So guess what... time to start messing with stuff.

I want to put an analogue indicator in the face plate of my leach amp case that will monitor the temperature of the output transistors. This is more of an asthetic consideration, but I think it would be cool to have a rough idea of the operating temperature.

I was planning on using the movement out of an old multimeter, but what I was wondering is whether there is an easy to impliment this.

1) Are there any voltage differentials that I could hook up the meter to which change in relation to the temperature of the amp?

2) If not, is there a simple circuit which could accomplish this?

I don't really care how accurate it is, as long is it gives a rough idea of when the amp is cold and when the amp is hot. (again, asthetics mostly)

Thanks Guys,

Wes

[blu_line]

Ok, heres the deal. I just finished getting my system working nicely. (Leach amp, Bass Amp, Active Crossover, Hybrid ESL's) So guess what... time to start messing with stuff.

Need !!!!!
Did you build the ESL y'r self ?
Is the Leach amp able to drive the ESL Transformers ?
How does is sound, an hybrid ESL with active X-Over ?

grtz

Simon

[wrl]

Yep, built them myself. I'll post pictures when I get around to it someday. I must mention that although I built them myself, I got tons of advice from both this board and from other people (so I can't take all the credit).

The leach amp does a fine job of driving the esl X-formers. If you want the specifics of my setup I'll be glad to post it. I have a minimum of 1-ohm resistor in series with the input. This seems to make the leach amp a little happier. It sounded a little harsh without the resistor.

The active crossover sounds beautiful in this setup. I really prefer it to a passive setup (both sonically and because it allows for much more adjustibility). I used Sheldon's design off of his websight (www.quadesl.com) and it works quite well.

Let me know if you want more info-

Wes

[peranders]

You could use a LM3914 and some temperature sensor, AD590, LM135, plus many more.

[wrl]

Thanks peranders,
Could I get the info on how to impliment those off of the app notes from national? Also, would I need a seperate power supply for this, or could I pull from the same transformer I used for the amp boards?

[peranders]

Check first how you make an interface for a tempsensor, then check the LM3914 which is a plain analog voltmeter.

Convert the signal (0-100 deg C or F if you prefer it) from the sensor to 0-10 V or so. You will need max 15 volts and you can use some power from the amp because the sensor can be related to any potential. If you don't have 15 volts you can easily fix this with a simple regulator consisting of a power transistor (darlingtion maybe) and one zener plus a resistor, plus a few caps. Maybe you must the the transistor on a heatsink. You can also check how you do a power regulator (which can take high voltage) out of a LM431, check the datasheet for this shuntregulator.

National has lot's of sensors and I gather lot's of application notes. Haven't checked though how good or practical they are but they usually are one the best.

[pooge]

Leach made a correction to his protection circuit to make it less sensitive to ESL-type loads in April 02. Did you get that fix? The amp is otherwise very stable into such loads.