LM339 RELAY DRIVER
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lm339 "open collector" question...
Pete The threshold is adjusted with the resistor divider - you can simply use a potentiometer wiper with 5v to the top of pot, gnd on the bottom as a variable V reference. The LM is open-collector and will need proper biasing that a series resistor will not give. I see Rslay can also relaay an AC power source from your schematic. If I hadn't written " final? It's pretty easy with a comparator.
Power supply is 7VDC. Comarators are used with low currents. Comments 19 Comments sorted by Date Added Votes. Also, the 10K resistor, which is biasing the transistor and controlling the base current, may be too large not enough current gets through the transistor to light the LED.
Working with the Comparator Circuit | ermicroblog
The circuit is to use the LMN-which seems right to use- which I dont fully understand so far how it work. Now, the question is, what value of R5 do we need if we want V to change by 0. If you could help me with the schematics, it will be a mercy on me, Waiting for your help Cheers Dear. Otherwise, I think I have added everything as you said, and as given.
Note that the relay is driven by a power transistor. Its feedback and input resistors are internal. So I have added a transistor which switches current to the relay. It drives a TIP31 which is a medium power power transistor. In particular, my temperature to turn on the relay should be 33 degrees F ohms and turn off at 36 degrees F ohms.
Even with hysteresis it switches the relay so fast the relay melts from the arcs.
The LM is designed for single supply operation. I have a voltage divider made from Supply A's voltage level, to give 0.
You may want to put a diode in series with your transistor base lm39 well since the output of the LM will not saturate to 0V. Usually it being used as the zero crossing detector circuit, where it takes two analog inputs and compares them; then produce the interrupt according to the voltage input level on both input. If anyone of you are interested, this is how I drew it up for my final breadboarding. I will change it to a different op-amp.
The 8K2 in the base of the power transistor will only give a base current of 1. rdlay
So, how if I want my infrared sensor to detect black colour surface? Post Your Answer Discard By clicking "Post Your Answer", you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.
Oct 2, 5, 1, He will have to use a transistor to drive the relay.
Also--"Audioguru"can you recommend a different Comparator that may better handle this current? When the open collector output of the comparator is turned on current flows through the 1K resistor relau the base-emitter junction turning on the transistor completing the circuit for relay K1 and the LED on indicator. Therefore don't miss it, stay tune on this blog!
LM Quad Voltage Comparator IC Design Kit (#) | NightFire Electronics LLC
For a better experience, please enable JavaScript in your browser before proceeding. An LM is the same but is a dual cpmparator.
You will want to add the things that were suggested earlier such as the snubber, flyback diode, voltage divider and pull-up resistor on the output of the LM since it is open-collector. The comparator is set to see this voltage change, and sends the signal to the coil to activate the relay and switch power to the BAP enhancer.
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