Comments on this symmetric design - Page 6

danfo098 · 15th November 2009, 02:51 PM

To get the quiescent current I measure the voltage drop over the 0R1 emitter resistors (both at 3.7 mV with R36=0R). To get the total current I've measured the current coming out/in of/to the +-50 V rails with my multimeter in series and the bench supplies also confirms 120 mA.

The bench supplies show 25 V in the video but it's a 2x0-30 V supply with a button to series connect both supplies so it's 2x25 V per supply.

I haven't done any more measurements. The card is so compact and packet with components that it's hard to get access without accidentally shorting something.

I forgot to include the zener current for the cascode biasing so the total should be 81 mA.

danfo098 · 15th November 2009, 11:16 PM

I've done some further measurements on the total current consumption and now my multimeter shows 90 mA on both rails (it's a velleman DVM92, I really need to get a better one). I also revisited the simulation and it says 94 mA on the positive rail and 92 mA on the negative rail (with 39 mA quiescent current) so now it seems that all the currents do add up.

However the bench supply still shows 120 mA but I don't trust it.

The dc offset is 2 mV according to the velleman, (simulator says 17 mV).
I've also measured the voltage drop over the 22R filter resistors ~0.9 V and that checks out with the simulator.

Now I need to get a scope and a signal generator to.

mightydub · 16th November 2009, 05:13 AM

Congratulations on successful power up! The best sounding amp is always the one you just built yourself.

What are you using for R47, R48 (the output emitter resistors)? The package looks impossibly small.

danfo098 · 16th November 2009, 07:39 AM

Thank you.

The output emitter resistors are caddock MP930 0R1 30 W, and they are mounted on the heatsink.

http://www.caddock.com/Online_catalo...000_Series.pdf

mightydub · 16th November 2009, 09:51 PM

Interesting! thanks for the link.

danfo098 · 17th November 2009, 01:07 AM

Here are some high resolution pictures as promised.

SimSym Amplifier High Res Pictures

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15th November 2009, 02:51 PM	#51
danfo098 diyAudio Member Join Date: Apr 2005 Location: Linköping	To get the quiescent current I measure the voltage drop over the 0R1 emitter resistors (both at 3.7 mV with R36=0R). To get the total current I've measured the current coming out/in of/to the +-50 V rails with my multimeter in series and the bench supplies also confirms 120 mA. The bench supplies show 25 V in the video but it's a 2x0-30 V supply with a button to series connect both supplies so it's 2x25 V per supply. I haven't done any more measurements. The card is so compact and packet with components that it's hard to get access without accidentally shorting something. I forgot to include the zener current for the cascode biasing so the total should be 81 mA.

15th November 2009, 11:16 PM	#52
danfo098 diyAudio Member Join Date: Apr 2005 Location: Linköping	I've done some further measurements on the total current consumption and now my multimeter shows 90 mA on both rails (it's a velleman DVM92, I really need to get a better one). I also revisited the simulation and it says 94 mA on the positive rail and 92 mA on the negative rail (with 39 mA quiescent current) so now it seems that all the currents do add up. However the bench supply still shows 120 mA but I don't trust it. The dc offset is 2 mV according to the velleman, (simulator says 17 mV). I've also measured the voltage drop over the 22R filter resistors ~0.9 V and that checks out with the simulator. Now I need to get a scope and a signal generator to.

16th November 2009, 05:13 AM	#53
mightydub diyAudio Member Join Date: Dec 2006 Location: Where the sky loves the sea	Congratulations on successful power up! The best sounding amp is always the one you just built yourself. What are you using for R47, R48 (the output emitter resistors)? The package looks impossibly small.

16th November 2009, 07:39 AM	#54
danfo098 diyAudio Member Join Date: Apr 2005 Location: Linköping	Thank you. The output emitter resistors are caddock MP930 0R1 30 W, and they are mounted on the heatsink. http://www.caddock.com/Online_catalo...000_Series.pdf

16th November 2009, 09:51 PM	#55
mightydub diyAudio Member Join Date: Dec 2006 Location: Where the sky loves the sea	Interesting! thanks for the link.

17th November 2009, 01:07 AM	#56
danfo098 diyAudio Member Join Date: Apr 2005 Location: Linköping	Here are some high resolution pictures as promised. SimSym Amplifier High Res Pictures

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