mixing single and dual supplies in bargraph circuits

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JAY X

Well-known member
Joined
Jan 9, 2009
Messages
683
Hi All!

I'm designing a rectifier buffer with tl072 dual supply opamp. and the bargraph with lm3914/15 with single supply. ¿is there a problem mixing single and dual supplies? Otherwise i'm looking for a fet opamp for single supply.  Supply rails are +/-15v.

Jay x
 
I might be wrong but i think you'll be OK with that. Once the signal is rectified, it should no longer have negative swings, so lm3914 would be fine.

Anyway, the TL072 could be used with a single rail supply, but you would need to biased the input signal to 1/2VCC.

Thomas

 
JAY X said:
Hi All!

I'm designing a rectifier buffer with tl072 dual supply opamp. and the bargraph with lm3914/15 with single supply. ¿is there a problem mixing single and dual supplies? Otherwise i'm looking for a fet opamp for single supply.  Supply rails are +/-15v.

Jay x
The only potential issue is trying to drive an IC input pin running from a single supply to a negative voltage. The ICs usually have an intrinsic body diode that will start conducting and might release smoke if driven negative by a low impedance.

If the +/-15V circuit is limited to not drive the +v circuit inputs negative you will be fine. 

JR
 

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