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Good news Brian!! I got part of it working now!!!
I plugged the radio into the pic and recording chip. When i talk to it, it records the message, and then re-plays on a speaker coming out of the ISD1790P. Now, i just have to put some de-coupling capacitors from the speaker output and maybe a...
Ok, i put a voltmeter across the two pins identified in the first picture. One is ground, the other is speaker +. When the radio is not receiving anything, it is zero volts. As soon as the radio is receiving a message, it jumps to 1.97 volts.
Here is a pic of the other side of the board, these...
I measured it from ground to the positive of the speaker output. It is zero volts when nothing is happening and 1.97 when the radio is receiving.
As you can see in the pic, there are 3 pins. The lowest one is ground (green wire), the middle is the speaker output (red wire), and the top is the...
Alright, just a little update. When radio number 1 transmits to radio 2 (the one with the headset) i measure 1.97 volts, using a voltmeter, coming out of the headset, no matter the volume on the radio 2. And zero volts when radio 1 isnt transmitting.
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Hi Brian,
im still keeping up with you here. Ive just been extremely busy lately but i will be working on this project tomorrow. That schematic that you provided will be to amplify the signal(boost the voltage) coming out of the radio so it can be read more accurately by the ADC on the...
So that schematic you drew will be the amp to amplify the signal coming from the radio. This will then be fed into the micro-controller, which will be used for triggering purposes, and then into the recording chip to be recorded.
The sound then coming out of the recording chip will have to be...
Ive always been confused when it came to biasing transistors, your explanation is helping me. So i guess the bias current will depend on the voltage coming out of the radio then?
And the way i understand it, is, i could use a 0.1uF capacitor for Cc?
The other capacitor you are referring to...
In referance to the capacitor, thats what the "Cc" capacitor and "Rb" resistor do, right? (in the diagram from the link i posted above)
the diode would just be in series after the amp because of the 0.7 volt drop?
So the radios im using are the Motorola SX700. These radios have the VOX option. I think i will use that function.
Just a basic NPN transistor amp, like the one in the link below, will work for me?
The basic transistor amplifier
OK, so if the voltage is 4V P-P, i may not have a problem, but if i do, i will amplify it.
Now my other question.
How can i take the signal from the recording chip and get it to transmit on the radio?
Lets say somebody is talking on the radio with a headset, they have to press the PTT button...
Thanks for your help so far Brian,
Now i got the programming working, but my next problem is signal voltage. Not sure if i said it earlier, but im building a simplex repeater for two way GMRS radios. I havent tested it yet with the radios( im using music from my computer right now) but i...
Ok,
in regards to the diode / rectifier. Since my input voltage is fairly low, when i pass the signal through the diode i will see a .7 volt drop. Will this not totally eliminate the signal voltage?
And in regards to the other variable that i need. At the bottom of my code, i put a variable in...
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