Building an LDR-controlled relay kit with hysteresis/delay for on and off transitions (LM393 comparator with RC-dampened inputs).
Here's a quick demo..
Another cheap little kit from aliexpress. I love'em!
This circuit demonstrates how to use a light-dependent resistor to switch a heavy lead (via a relay), but with a dampening delay implemented with an RC circuit squashing the inputs to an LM393 comparator.
From aliexpress, but probably widely available with similar specs.
| Ref | Item | Qty |
|---|---|---|
| R1 | 4.7kΩ | 1 |
| R4,6 | 10kΩ | 2 |
| R3 | 10kΩ pot | 1 |
| D3 | 1N4007 | 1 |
| Q1,2 | 805 | 2 |
| C1 | 104, 100nF | 1 |
| C2 | 10µF | 1 |
| J1,2 | 2 x 2pin headers | 4p |
| J4 | KF301-3P, 3pin terminal block (missing/not included in the kit) | 1 |
| R2 | 510kΩ | 1 |
| R5,7 | 2.2kΩ | 2 |
| D1 | Red LED 5mm | 1 |
| D2 | Green LED 5mm | 1 |
| U1 | LM393 | 1 |
| U1 | DIP8 socket | 1 |
| J3 | DPDT switch | 1 |
| K1 | relay | 1 |
| J2 | LDR | 1 |
| PCB | 1 |
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