Separate adjustments are provided for preset turn-on and turnoff voltages. — «Signet- ics Analog Data Manual,’ CA, 1977, p 731. Signetics, Sunnyvale, AUTOMOTIVE CIRCUITS 85 +12v. from car lOKfi BATTERY MONITOR— Basic circuit energizes LED when battery voltage drops to level set by 10K pot. Audio output may be con- nected directly to high side of voice coil of car radio loudspeaker without affecting operation of radio. Article also tells how traffic radars work. By adding 10.5-GHz oscillator, same cir- cuit can be used in 10.5-GHz amateur radio band for communicating with other cars using this band.
Output-sensing amplifier using from 1000 ohms to infinity, using either IC, has gain of 19 over audio band. Tr 2 stage is switched or variable components. Can be used remotely by con- necting external meter at J2. L1 is tuned by CI for 80 or 40 meters. Difference is then inte- grated and fed into denominator of divider-con- nected AD533J as control signal V*. Average AC output is held within 1% of 7 V. — R. Frantz, An- alog Multipliers — New IC Versions Manipulate Real-World Phenomena with Ease, EDN Maga- zine.
When con- trol input is high, CR1 is off and current devel- oped by Rsain flows into rectifier input, allowing audio to be amplified. Values for L1 and’ C1 are chosen to cover desired frequency range. Measures 18 » x 17″ x 10″ inches, and covers all bands, 160-15 Meters, including WARC and MARS (80% of full output set to nearest amateur band). 10/12 Meters modifiable. Diode balanced modulator at upper left can use individual 1N63 or 1N914 diodes, or RCA CA-3019 hex diode array that also provides diodes for RF clipper. When youre ready . . you can add a powerhouse linear amplifier at no additional cost.