EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Happyhopper on August 17, 2019, 10:46:30 pm
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Anyone know of a read relay at say 1 .v trigger?
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A bipolar transistor "triggers" at 0.7V and that can be used to drive a relay.
What's your ultimate goal?
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To use a mp3 player as a control for a 3 volt motor thank you for your help
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I'm going to guess that you want to trigger a relay when the audio level is greater than a certain amount. If that's not the case you gotta give us more details on what you really trying to do.
Here's a very straightforward idea:
- get a LM3916 and a 555
- build the standard VU-meter circuit that is described in the datasheet; there is also an instructable here:
https://www.instructables.com/id/LM3915LM3916-VU-Meter/ (https://www.instructables.com/id/LM3915LM3916-VU-Meter/)
- the LM3916 VU-meter will operate from it's own supply, like +5V
- wire up the 555 as a "monostable multivibrator" which will activate a 5V relay on its output;
https://www.elprocus.com/monostable-multivibrator-using-555-timer/ (https://www.elprocus.com/monostable-multivibrator-using-555-timer/)
- use one of the LED outputs of the LM3916 to activate the trigger input of the 555; which one you choose will determine the trigger level
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The LM3915 and LM3916 are obsolete, not made anymore and not in stock at Digikey.
The LM3914 is still made and available only in a tiny, impossible to solder, surface mount package.
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To use a mp3 player as a control for a 3 volt motor thank you for your help
Can you elaborate on this?
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Anyone know of a read relay at say 1 .v trigger?
Why do you open several threads and so cryptic? Why don't you explain well what you want and all in one thread? Please don't waste people's time!
I would like to use my mp3 player as a signal generator to relay a3volt power supply , was going to make my own by use of a read relay question is there a better way
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