Discrete OP Schemtic for +/-60 V

[Madman]

Hello All, :grin:

i was searching for a Schematic of a Operation Amplifier with +/- 60 V OperationVoltage.

Can anybody help me? :roll:

Nice Day!

Dennis

 

[gyraf]

You may want to look into driver circuits for power amplifiers.

Why that high a voltage?

Jakob E.

 

[Samuel Groner]

Basically any discrete opamp will work if you use suitable transistors and keep the dissipation low enough. The second constraint get's hard pretty soon, especially if you want an short-circuit proof output.

I have one for +/- 40 V in development--preliminary release:
[removed]

Skip Q11/Q12 and R10/R11 if you try to implement that one. Q1/Q2 are 2SA970BL, Q9/Q10 MJE172/MJE182 and R1/R2 could get paralleled by a 22 uH each for lower noise.

I'll post an updated schemo with more changes if you are interested--but need to fix that :evil: Wind*ws first...

And you could check www.apexmicrotech.com for schematics and buyable opamps.

Samuel

 

[bcarso]

Agree with Samuel on Apex---they have been specialists in HV op amps for many years now. Be careful about taking their schematics literally however.

For the highest performance output stage I have seen some Sanyo transistors for video applications that look quite promising.

 

[Samuel Groner]

For the highest performance output stage I have seen some Sanyo transistors for video applications that look quite promising.

Tell me more! :grin: (Do you know Eliza?)

Samuel

 

[bcarso]

[quote author="Samuel Groner"]

For the highest performance output stage I have seen some Sanyo transistors for video applications that look quite promising.

Tell me more! :grin: (Do you know Eliza?)

Samuel[/quote]

Hmmm---now that I look at them they are only 80V Vcbo. Maybe they have some higher voltage ones that are almost as fast. This pair is the 2SA1402/2SC3596.

Who is Eliza?

 

[PRR]

> Who is Eliza?

I met Eliza in her preteen years. She looked like a TeleType but really lived in a mainframe. She was a better conversationalist than most people I knew.

http://www-ai.ijs.si/eliza-cgi-bin/eliza_script

Eliza: Hello. I am ELIZA. How can I help you?
You: I need a good BJT for an opamp.
Eliza: Why do you want a good bjt for an opamp?
You: So that my clients will love me.
Eliza: Why do you say your clients will love you?
You: The sound will be wonderful.
Eliza: Please go on.
You: Harmonious and powerful.
Eliza: Please go on.
You: And there is another thing....
Eliza: Please go on.
You: I hate mice in my gear rack. +/-60V will kill the little pests.
Eliza: Why do you say your gear rack 60v will kill the little pests?
You: Edison proved it, to spite Westinghouse.
Eliza: Please go on.

As you see, she has stock phrases. This version uses "Please go on." a lot; Samuel has met her when "Tell me more!" was a favorite conversational tidbit. Eliza has a brother who pretends to be a psychotherapist.

ELIZA--A Computer Program For the Study of Natural Language Communication Between Man and Machine

http://en.wikipedia.org/wiki/ELIZA

 

[bcarso]

Oh oh oh yes. Of course. She says tell me more a lot.

I thought maybe Eliza was someone Samuel knew at Sanyo :grin:

At a party years ago we had two programs talking to each other, one of whom was Eliza. The concept was great but it didn't get too far.

 

[Madman]

Hello jakob,

i need the schematic for +/-60 for a passive EQ, for example the SPL EQ´s working with 120 V for a bigger Headroom.
For this operation with a passive EQ was i searching for a OP as Pre AMP, with +/- 60 V or other.

Thanks

Dennis

 

[Samuel Groner]

This pair is the 2SA1402/2SC3596.

Hell--700 MHz ft for a 8 W!

I need the schematic for a passive EQ, for example the SPL EQ's working with 120 V for a bigger headroom.

I suggest that you stay with +/- 40 V; this is only about 3 dB less headroom than a +/- 60 V and it is much easier to design and to source good parts for.

IMO supply rails higher than +/- 24 V are pointless and usually lead to design compromises with worse audio performance. My high-voltage opamp is basically a "fun" project and not because I believe that there is any advantage in using such high supply rails.

BTW, I believe that the company we all know of uses opamps similar to this one: [removed]

Replace the two current sources (Q5/Q6) with dual transistor ones and Q7/Q8 with modified darlingtons and you get the same transistor count. No miller compensation probably.

Samuel

 

[bcarso]

[quote author="Samuel Groner"] Hell--700 MHz ft for a 8 W!


Samuel[/quote]

Moto used to make some higher-voltage comparable-power parts that were also quite fast, for the same application, but evidently abandoned the business even before they sold that portion of the company to On Semi. Sigh...

 

[Samuel Groner]

Does it happen that you know a source for these Sanyo parts, Brad?

Samuel

 

[bcarso]

[quote author="Samuel Groner"]Does it happen that you know a source for these Sanyo parts, Brad?

Samuel[/quote]

Not a clue. Let me know if you track them down.

 

[Samuel Groner]

Said, done: www.bdent.com

However, I had troubles ordering from them last time as my bank refused to transfer the money. If you order some, let me know perhaps we could arrange something.
Samuel