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| Joined: | Feb 23rd, 2007 |
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I've been posting information in the regular EVP forum about building boxes, the latest being instead of using the Radio Shack 12-469 in "hack" mode as many are doing, I use my linear sweep circuit to sweep the tuning, and use the radio as tuner module in a "box".
Previously I used a timer chip to provide a remote turn on for the radio, so it's power button doesn't have to be pushed to turn it on. There was still a couple minor problems I wanted to address. One is a battery voltage monitor, which is very important if I use Gell Cells. The other is knowing what band the radio is on. When first turned on, it's on FM. There is a pin on the header that changes voltage, goes to about 2 volts, when the radio is in AM, so I used that to trigger a transistor, and turn on an LED. The voltage monitor is also just simple transistor switch that turns on a red LED when the batteries drop to about 10-1/2 volts. It's not good to discharges the 12 volt gel cells below 10 volts, they can be permanently damaged.
In the video, when the red LED is on, the radio is in AM.
I'll get schematics up later on.
Old-Frank
Attachment: 042108-36-WithAM-Indicator.3g2 (Downloaded 1022 times)
Last edited on Apr 21st, 2008 09:36 AM by Old-Frank