High Voltage Op-amp

Thread Starter

Hymie

Joined Mar 30, 2018
1,277
I have a design proposal based around the use of op-amps – I’m seeking an op-amp having a supply voltage of at least 48V (+-24V) and being reasonably priced (ideally less than $1), with through-hole construction. Other parameters are unimportant for the purposes of the circuit.

I would be grateful anyone could suggest suitable op-amps or direct me to a list of op-amps that includes their supply rail details.
 

OBW0549

Joined Mar 2, 2015
3,566
I don't think you're going to find a whole lot; the cheapest ones I was able to locate on Digi-Key, all in the $5-6 price range, were the OPA604, OPA552, OPA551, and the LM675.
 

Thread Starter

Hymie

Joined Mar 30, 2018
1,277
Hello,

Would the audio opamp LM1875 do?
That can work on 60 Volts max.

Bertus
It’s a possible, but I don’t need high power, just high voltage – so something cheaper might be available.
 
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Thread Starter

Hymie

Joined Mar 30, 2018
1,277
Depending on what you want to do some OP-amp inputs can exceed the supply rails. You can also look at Norton OP-amps.

https://www.apexanalog.com/ has high voltage OPamps.

So, it;s like what do you need. Inputs being high voltage? Outputs being high voltage? What sort of function (OP-amp, comparator etc)
Good point – it is the inputs that will be at high(er) voltage (not necessarily the output), used in a comparator configuration.
 

OBW0549

Joined Mar 2, 2015
3,566
Good point – it is the inputs that will be at high(er) voltage (not necessarily the output), used in a comparator configuration.
If that's the case, you might want to look at Linear Tech's (owned now by Analog Devices) "over-the-top" series of op amps; these allow the inputs to go to high voltages and still function, regardless of supply voltage.
 

OBW0549

Joined Mar 2, 2015
3,566
You can also do something like this, with just about any old op amp:

COMPARATOR.png

U1 can be just about any op amp, since its inputs are always at GND potential. As drawn, the op amp must be operated from a bi-polar supply. R1 and R2 must be equal, as must R3 and R4. R5 may be sized according to how much threshold adjustment is desired.
 

Thread Starter

Hymie

Joined Mar 30, 2018
1,277
Thanks to all of you for your input; I found a Chinese seller on ebay selling LM1875 op-amps at less than 50p each.

So a special thanks to bertus for the suggestion, with the advantage that the op-amp can directly drive the relays in my design proposal.
 
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