ISD1420 voice recorder question

[DaveTV]

I was thinking about playing around with a looper circuit based around the ISD1420 voice recorder chip--I know, not a very original idea.

The chip's output pins are intended to drive a small 16 ohm speaker with about 12 mW of power. Instead of a speaker, I was hoping to put some sort of opamp buffer in its place so that it could be used as part of a pedal. Would it be okay to connect the chip's speaker outputs to a standard opamp, or is 12 mW too much power to feed something like a TL072?

[The Tone God]

I don't know if it was the 1420 but I know some of the ICs in that family have an output for things like opamps and transistors.

As always check the spec sheet.

Andrew

[niftydog]

12mW is a typical rating, specified into 16ohms. The datasheet also says that the max voltage across the speaker pins is 2.5Vp-p into 600ohms.

Take a typical op amp with an input impedance of say 10kohms and the max voltage output of 2.5Vp-p... 250µA & 625µW!!!

Op amps are (generally) voltage controlled devices, so as long as you don't exceed the input voltage spec for the op amp you should be fine.

[puretube]

you won`t need a buffer - that speaker-output is the output of a buffer already....

just watch out for DC offset (output-cap)

[DaveTV]

Thanks for all the great info everybody. My plan was to feed + and - signals from the speaker outputs into a difference opamp circuit and I just wanted to make sure I wasn't going to damage anything. From that point I was going to blend the looping signal with the dry signal.