PIR sensor - wake and sleep using CH_PD & thingspeak update.

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Re: PIR sensor - wake and sleep using CH_PD & thingspeak upd

By Barnabybear
- Sun Feb 19, 2017 3:40 pm #62780 Hi, looking at the schematic there is a 1K resistor (R14) in the output of this PIR. This is forming a voltage divider with the 10K and dropping the voltage at the pin. Try removing the PIR and leave the resistors and the diode in place. Apply 3.3V to the Anode of the diode, if this works then it looks like the 1K resistor is the problem. The is only one 1K resistor on the board, it's next to the ground pin marked 102. Your going to have to short this out with a small piece of wire. You might want to test this first, if so remove the output wire from the pin and touch it onto the end of the resistor nearest to the corner of the board. Hope that helps.
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Re: PIR sensor - wake and sleep using CH_PD & thingspeak upd

By Barnabybear
- Tue Feb 21, 2017 7:12 am #62833
jhumphr wrote:Putting a switch after the diode works, but very infrequently. Putting the switch and removing the diode works every time. This would make me believe the diode is causing the problem, but how can that be so?


Hi, I'm glad you're part way there. There is always some volt drop across a diode and it sounds like there is to much for the set of components your using. Can you let us know which one you're using please. Silicon diodes will drop something like 0.5V where as germanium diodes are more like 0.2V, I used a 1N4004 in the original build without any problems but didn't use that PIR. Have a look round and see if you can pick up some thing like a 1N34A or just any diode with a low forward voltdrop.
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Re: PIR sensor - wake and sleep using CH_PD & thingspeak upd

By jhumphr
- Tue Feb 21, 2017 12:47 pm #62848
Barnabybear wrote:Hi, I'm glad you're part way there. There is always some volt drop across a diode and it sounds like there is to much for the set of components your using. Can you let us know which one you're using please. Silicon diodes will drop something like 0.5V where as germanium diodes are more like 0.2V, I used a 1N4004 in the original build without any problems but didn't use that PIR. Have a look round and see if you can pick up some thing like a 1N34A or just any diode with a low forward voltdrop.


I'm using a 1N4003, which should function the same as the 1N4004 in this scenario. What PIR are you using?
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