Compact Sized LME49810/11 +ThermalTrak Amp

[dirkwright]

You probably won't come up with a matched pair. Just adjust the Re resistors to get a reasonable balance between the p and n.

That's fine for DC but not for AC.

 

[klewis]

That's fine for DC but not for AC.

You may know more about this than me, but, I (and several others ) used it to good effect on the Fetzilla Amp where we couldn't find matched pairs.

 

[dirkwright]

You may know more about this than me, but, I (and several others ) used it to good effect on the Fetzilla Amp where we couldn't find matched pairs.

I've been reading Bob Cordell's book. It's excellent!

 

[jackinnj]

I don't see NJL3281 and NJL1302 on your site.

You have 2 flavors to choose from. If you read all the datasheets...

 

[woodturner-fran]

/just posting here to subscribe.

I'm almost finished building one of Panson's compact amps, the build has gone well, and initial testing is promising.

Fran

 

[powerflux]

Panson, i suspect that if you'd put your driver transistors on the same heatsink as the thermaltraks' your bias-drift problems will be over. No need for extra diodes..

 

[panson_hk]

Panson, i suspect that if you'd put your driver transistors on the same heatsink as the thermaltraks' your bias-drift problems will be over. No need for extra diodes..

Hi, I prefer the drivers temperature not being modulated by the output devices.

 

[Idefixes]

Hi panson,
I bought 2 of your latestet revision board from someone that forgive project. I purchase all parts i needed as i have some as driver and transistors on hand. I have choice for ThermalTrack Unit between NJL3281/1302 and NJL42381/4302. Do you see an issue in using the second one as it has better SOA charts? I have MJE15030/15031 to but also 2SC5171/2SA1930. Could it be some stability issu in using this faster devices instead of MJE brand?

Marc

 

[panson_hk]

Hi panson,
I bought 2 of your latestet revision board from someone that forgive project. I purchase all parts i needed as i have some as driver and transistors on hand. I have choice for ThermalTrack Unit between NJL3281/1302 and NJL42381/4302. Do you see an issue in using the second one as it has better SOA charts? I have MJE15030/15031 to but also 2SC5171/2SA1930. Could it be some stability issu in using this faster devices instead of MJE brand?

Marc

Hi Marc,

No problem at all to use 4281/4301. I used have them.

It should be find to use 5171/1930 to drive one pair ThermalTrak in this Compact Amp, though their current rating is lower.

Cheers,
Panson

 

[Idefixes]

Hi Marc,

No problem at all to use 4281/4301. I used have them.

It should be find to use 5171/1930 to drive one pair ThermalTrak in this Compact Amp, though their current rating is lower.

Cheers,
Panson

Tanks for reply, i know 5171/1390 current rating are lower as 15030/15031 but for +/-35Vdc rail use and driving one pair NJL4281/1302 it's more then enough i think, my only concern was on stability issue as they are a lot faster as onsemi devices.

Marc

 

[panson_hk]

don't worry for stability. no problem.

 

[Idefixes]

don't worry for stability. no problem.

Ok , thanks, than i will build with NJL4281/4302 and 5171/1930.

Marc

 

[panson_hk]

please post your result here. have fun!

 

[Idefixes]

Hi panson,

Parts are solderer on board only NJL are not. I have on hand heatsink that mesure 300x75mm with 40mm thick (30mmfins and 10mm base). Would one so heatsink per amp board sufficient?

Marc

 

[Eddie2]

If I am allowed to give an answer to that question, I would say that such a heatsink
is large enough. But, if it would still get hot, you better mount a fan in front of it.
No, NO PANIC !! It does not need to run ful speed !!
A very slow running fan makes a heatsink so much more effective, that a smaller
heatsink is large enough, (and cheeper) or keeps it much cooler.
You never hear that fan !

Kind regards,

Eddie

 

[Idefixes]

Here they are. NJL devices will be soldered when mounting on heatsink. I have to mount LME49810 and driver heatsink too.

Marc

 

[panson_hk]

Here they are. NJL devices will be soldered when mounting on heatsink. I have to mount LME49810 and driver heatsink too.

Marc

Nice build! The heatsink should be big enough.

 

[emerth]

If I am allowed to give an answer to that question, I would say that such a heatsink
is large enough. But, if it would still get hot, you better mount a fan in front of it.
No, NO PANIC !! It does not need to run ful speed !!
A very slow running fan makes a heatsink so much more effective, that a smaller
heatsink is large enough, (and cheeper) or keeps it much cooler.
You never hear that fan !

Kind regards,

Eddie

Absolutely agree with Eddie.

 

[Eddie2]

Thanks !

 

[panson_hk]

2nd generation board

I want to make a 2nd generation of this amp board. A Baker clamp as shown in Fig. 17.2 of Bob's book is being considered for LME49811. A sketch is show below. Any comment?