The post discusses a simple PIR motion sensor circuit shared by one of the interested members of this blog.
This is my smallest, cheapest, foolproof etc. movement detector with dim-switch that works in all conditions. In the drawing "tv" means "or similar". Enjoy! I have operated the circuit with 2½-9V, but maybe ca 5V is the best. So I bought 4 off cheapest possible solar garden lamps with rechargeable batteries. Price 2 euro per piece.
So now I'm going to put together four solar cells, four AAA-batteries and one 5252F (I have three ICs as spare parts!). The necessary coil is also included in the lamp, so I don't need to buy any parts. Enclosed the PCB with parts. The PIR has to be in the middle of the board and also the place of the two fastening screws are mentioned. So, make a big hole in the plastic box and/or in the PCB for the PIR and put all together. I don't know why it shouldn't work, but we'll see. Thumbs up!
PCB design for the proposed PIR Motion Sensor Circuit