- Joined May 18, 2020
This is the Data Sheet for the Relay i would like to use 12v Subminiture PCB Signal Relay 1A SPDT HFD41Just replace the 5V relay with the 12V relay. Would help to know coil resistance or coil current to figure 2N2222 new base resistor.
https://www.ebay.co.uk/itm/1-10pcs-...var=512646049444&_trksid=p2057872.m2749.l2648Late to the party, working on a slightly different approach. Can you post a link to the PIR module you are using? There are lots on ebay, but I didn't see one that looks like your image in post #1.
Interesting.... I hadnt considered using other than NE555 as i am not very electronic savey, i am old school using relays. This seems a 'cheaper' option as i will need a lot of these modules. I will have to build a prototype on breadboard to see if it meets the requirements. As i dont have either a 2N7000 or CD4093 i will have to order a couple of each.First pass at a schematic. This uses a CMOS logic gate package to form a boxcar or pulse-stretcher type of monostable. Unlike a 555, this circuit's pulse ends no matter which state the SENSE-1 input is in, so the trigger signal does not have to be differentiated.
R1-R2-C1 set the red LED on-time. R2 should give approx 10-30 sec range.
A white LED has a forward voltage of around 3 V to 5 V, so you cannot run four of them in series on a 5 V source, or probably even on a 12 V source. This is why they are broken up into two strings. The POINT switch powers them directly, eliminating one relay or switching transistor.
D1-D2-D3 form a cute switching system that controls two different LEDs with only one transistor. In the normal case, Q1 is on, the green LED is on, and the white LEDs might be on depending on the state of the POINT switch. Because the forward voltage of a typical green LED (2.1 V) is less than the combined forward voltages of a typical red LED (1.8 V) and a small signal diode (0.6 V), the red LED is off, effectively "shorted out" by the green LED. When SENSOR-1 is activated, Q1 is turned off, the green LED is disconnected from GND, and R3 sources current through the red LED.
Depending on the SENSE-1 vs SENSE-2 timing, I might have to add another 1N914 diode across R1-R2 to shorten the recovery time.
*** R4 and R5 should be 390, not 390K.
ps. Another approach is to *** eliminate all ICs *** and use three 2N7000 transistors to do everything.
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by Jeff Child
by Jake Hertz
by Jake Hertz