FM receiver TDA7000 continuous loop scan

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brickman7

Joined Sep 29, 2013
1
New to electronics design, computer tech needs a schematic based on the simple TDA7000 ic to continuously scan through the frequencies! I have the TDA7000s, and YDA9088s but they are surface mounts. I can get most older ICs from a supplier in China so I'll take suggestions. I just need it as simple as possible. I have TDA2822s for amps, but I can get what is needed. I also have BB910 varactor diodes.

I just need an fm scanner to scan thru the frequencies and not lock on a station without having to be reset to continue scanning. And output thru an earphone and speaker. Also, I do not want to mute the scanning process. I need to hear the white noise as it scans.

Thanks!
 

Dodgydave

Joined Jun 22, 2012
9,951
Here is a circuit of a TDA7500 receiver using a varicap diode, you need to put a sweeping dc voltage instead of the wiper of the 100 k tuner pot, to scan through the wave band.

I would remove the 100k preset and use a triangle wave ramp generator like a 555 timer set to .1Hz to 0.5hz and buffer the the voltage across the charging cap to feed into the varicap diode.
 
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