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Motion detector lamp for my dog, which transistor config is suitable?
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MK14:
Using the components you seemed to say you have (PN2222 and 2N3904).
This should work, but I've not simulated or tested the circuit.
Where it shows the LED, you replace it with the 5V USB Leds.
EDIT: Updated circuit, to include (forgotten), current limiting resistor (100 Ohms).


FBMinis:

--- Quote from: james_s on October 26, 2018, 01:47:45 am ---An arduino? That's a ridiculous suggestion. Has everyone forgotten how to use small signal transistors? You could use a Darlington if you want a single device with sufficient gain. This should be a trivial project.

--- End quote ---

--- Quote from: MK14 on October 26, 2018, 03:04:17 pm ---Using the components you seemed to say you have (PN2222 and 2N3904).
This should work, but I've not simulated or tested the circuit.
Where it shows the LED, you replace it with the 5V USB Leds.
EDIT: Updated circuit, to include (forgotten), current limiting resistor (100 Ohms).



--- End quote ---

--- Quote from: JVR on October 25, 2018, 07:57:11 am ---Just use a small signal transistor to switch on the MOSFET. Its not like you care about switching times, so use the first transistor for what it is, a current amplifier. This will give you enough grunt to switch the mosfet.

--- End quote ---

Thank you for your clear and concise suggestions. Luckily I found a bag of BC517 in the back of a drawer and was able to setup 4 lamps using minimal amount of components. Total cost of each is less than an Arduino Pro Mini on Ebay.

FBMinis:
UPDATE

"I must be doing something fundamentally wrong and I'd like to ask for some advice. " - first post.

I found out what it was.

Please look at the schematic or at your PIR device, there's a resistor just before the OUT pin. This is working has the BASE resistor, usually with a value of 1K or 2.2K, hence only 3mA available to turn ON the transistor of your choice.

In my PIR sensors, I changed these to 220 Ohm, therefore now I can get 200mA Ic when using a 2n3904, or 300mA when using the BC337, for example.

No need for micro-controllers in this project.

Conclusion: these PIR devices already come with a BASE resistor.
ogden:
You are building IKEA Molgan LED lamp, Article Number: 602.637.29, 5.99$  :clap:

https://www.ikea.com/us/en/catalog/products/60263729/
FBMinis:
For 1/3 the cost and learning something while doing it,  not just being a consumer: win-win-win.  8)
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