EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: antenna on October 15, 2022, 06:48:19 am
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I have been trying to make the micro tracking transmitter on the talking electronics site here
https://www.talkingelectronics.com/projects/MicroBug%20Tracker/MicroBugTracker-P1.html (https://www.talkingelectronics.com/projects/MicroBug%20Tracker/MicroBugTracker-P1.html)
and each time I try, the oscillation (and LED) is on steady. It is supposed to chirp, but it just creates a carrier and stays on. This latest attempt was an expensive one as I ordered RF quality C0G capacitors and dollar a piece thin film resistors. The transistors I am using are BC848 and BC858. Anyone have any ideas why that circuit might just stay on??
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Did you read the part where it says that the LED is one of the flashing kind?
This type has an oscillator in it to make the LED flash, and it is this component that turns the BC858 on and off, which in turn enables and disables the BC848 RF stage.
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I blew right past that part. I never knew a "blinking LED" was a thing all by itself, I always figured it needed a circuit to make it blink. That explains why staring at that schematic for half the day offered no hints as to how it blinks lol. Thanks!