Need help? HT9170 OUTPUT DV PIN 15

[Audioguru]

So? If I use one amp side of the TL972 for the circuit in post #17.Then disable the second amp as your attach circuit in post #38. Correct?

Correct. Also connect a 100pf capacitor between the + input and the - input with short leads for the preamp opamp.
I always use shielded audio cable for a microphone even when the wires are only an inch or two long.

 

[cybertron]

OK?

How could I test the audio two see that its working correctly.Before i connect the output to the input on the decoder.
I don't have any test equipment other then a multimeter. Is there a very simple way to use the meter
for testing the output.If I'm get an audio signal.

 

[Audioguru]

How would you test the output of a mic preamp to hear if it works?
Simply connect it to the input of an audio amplifier to hear it.
Maybe use sealed earphones on the output of the amplifier and turn off the speakers to avoid acoustical feedback howling.

 

[cybertron]

How would you test the output of a mic preamp to hear if it works?
Simply connect it to the input of an audio amplifier to hear it.
Maybe use sealed earphones on the output of the amplifier and turn off the speakers to avoid acoustical feedback howling.

Can i use an audio amplifier from radio shack. It's there Mini Audio Amp with Speaker already build.
If I connect the the output of your circuit to the input of the mini audio amp would that suffice.
For testing your circuit. Would I get a signal output.
**broken link removed**

 

[Audioguru]

I have a Radio Shack mini-speaker. It is very sensitive. Its input is from a microphone, not from the output of a preamp unless its volume control is turned down to almost zero.

It (or any other amplified speaker) will produce acoustical feedback howling if it is in the same room as the microphone because the microphone can hear its output then any sound goes from the mic to the speaker then through the room to the mic to the speaker and through the room again to the mic to the speaker ....

If you wear sealed headphones then the mic cannot hear the sound and the sound does not go around and around.

 

[cybertron]

I have a Radio Shack mini-speaker. It is very sensitive. Its input is from a microphone, not from the output of a preamp unless its volume control is turned down to almost zero.

It (or any other amplified speaker) will produce acoustical feedback howling if it is in the same room as the microphone because the microphone can hear its output then any sound goes from the mic to the speaker then through the room to the mic to the speaker and through the room again to the mic to the speaker ....

If you wear sealed headphones then the mic cannot hear the sound and the sound does not go around and around.

So your saying it can work. If I use a pair of sealed headphones connect to the headphone output on the
mini-speaker, then connect your circuit output to the input on the mini-speaker.Correct? Is there an input on
that mini-speaker to connect the output from your audio amp.Reply!

 

[Audioguru]

You didn't hear me talk about the Radio Shack mini speaker in post #45:
"It is very sensitive. Its input is from a microphone, not from the output of a preamp unless its volume control is turned down to almost zero."

It works when a dynamic mic (coil and magnet kind) is plugged into the input. It will also work with an electret mic if the mic is fed through 10k resistor from a 9V battery to power the Jfet in the mic.

 

[cybertron]

If the mini-speaker is not going to work for testing the output signal on the pre-amp circuit in post #17.

What can I use to get a signal on the output to see if the amp is picking up any sound from the electret mic.

Can't use a multimeter.Or could I.

Then?

What do I use for testing the preamp circuit.

 

[cybertron]

If the mini-speaker is not going to work for testing the output signal on the pre-amp circuit in post #17.

What can I use to get a signal on the output to see if the amp is picking up any sound from the electret mic.

Can't use a multimeter.Or could I.

Then?
What do I use for testing the preamp circuit.

 

[cybertron]

Hello

How can i test the output for a signal when there audio pick from the Mic.
To see that the amp is pick up sound from the Mic for an signal output.
How can I hook up a cheap pair of headphone to the amps output.