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Topic: motion activated led strip (Read 200 times) previous topic - next topic


Hi guys. Could someone help me figure out the best way to make a certain circuit please?

What I'm trying to do is program an ATtiny85 along with some tip120 transistors, resistors, led strip, and a PIR motion sensor so that whenever the motion sensor detects something, the led strip turns on.

I know how to do most of this already but the trouble I'm having is power related. I want to connect my circuit to a wall outlet but since I'm not actually using an arduino im not exactly sure how.

Should I connect an SSR to my outlit/circuit, or would a wall outlet transformer be ok? How important do you think capacitors are in this circuit?

I want the circuit to use the least amount of power possible, just enough for the PIR to work, then once the PIR detects something, the circuit is given 12vdc for the led strip.

any advice/suggestions are greatly appreciated!! thanks


12V wall power supply.
A 5V regulator such as the 7805CV.

Use the 5V regulator to drop the 12V safe for the Attiny85.

Use the LED strip in parallel to the 5V reg.

Ensure the power supply is rated for the LED strip.


Oct 14, 2015, 11:46 pm Last Edit: Oct 15, 2015, 12:56 am by Wawa
A cheap PIR sensor can directly drive a logic mosfet (not a TIP120), that can turn on the LED strip.
There is a control on the PIR that sets the "on" time.
Most PIRs run on anything from 4-12volt (LED strip supply), and draw ~70uA.
No need for a micro.


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