On Jun 30, 1:38*pm, " wrote:
On Jun 30, 8:15*pm, whit3rd wrote:

On Jun 30, 11:38*am, "
wrote:

* * * I have built a mic amp and wanted to check the wave form on a
scope but when I connect the probes to the o/p of the amp the power
supply trips (The Mic operates on 9 volt single rail.)

Is one of your scope probes a GROUND connection? *Couple to the
microphone amp output through a coupling transformer, see if that
helps.

Which power supply trips, the scope, or the microphone amp? *What
are the specifications of that power supply?

Thanks
*no the ground connection of the scope is connected directly to the
Amp
Its the power supply connected to the amp that trips or reads about 4
volts instead of 9v
The current of the PSU was set to 1 Ampere.
Please, generally, how do you check the responds of an audio Amp on
the scope? I mean how the probes are connected.

need a good explanation of what is in that power supply

or, how about float the power supply, even better, use a battery.

then you should be able to connect your scope ground anywhere on the
circuit. just make sure your mike, amplifier, and power supply are all
floating.

Usually one connects the ground of the scope to the system's reference
point, also called ground, and connects the input of scope to the
output of the amplifier. If the output of the amplifier is an 'H'
drive, you will need two input probes, one for each output leg.

If you get the amplifier up and running there's a way to use your
sound card in your PC to explore what is happening at different
frequencies and what the bandwidth of your system is.