Hello everyone.

I recently bought these 5 meter fairy lights from the local market. It operates with a slide switch, one transistor, and one resistor.
I was just wondering how the circuit can flash by only using a transistor and one resistor, and what is the name of a circuit like this.

Pictures below.

Thanks you.

 

That is probably not a regular transistor but a small IC with a multivibrator circuit in it. Like you get with the flashing leds. All it needs is power and the thing flashes.

 

I doubt that is a transistor, more likely a dedicated 'flasher' chip. What is the top LH solder blob (circled in red below) connected to?

Edit: like this one: https://www.ebay.co.uk/itm/301124079844, though different pinout.

 

It is connected to the slide switch. On what looks like a transistor it has the letter G. Could this help?

 

Is it a N - channel MOSFET?

 

It is: (see PDF).
ADDED:

I doubt that is a transistor, more likely a dedicated 'flasher' chip. What is the top LH solder blob (circled in red below) connected to?

Edit: like this one: https://www.ebay.co.uk/itm/301124079844, though different pinout.

Standby current is 1...2uA (see PDF-2), so they ON/OFF LED only (pin "OUT").

 

Is it a N - channel MOSFET?

It has a MOSFET in there, probably a p-channel though looking at the polarities, plus a small oscillator turning the MOSFET on and off a couple of times/sec.

It is connected to the slide switch. On what looks like a transistor it has the letter G. Could this help?

Ah, just a ground to the switch case, plays no active role.

 

Thank you very much everyone. Very interesting.

 

I think it's an indication of where electronics as a hobby is going. Everything is becoming smaller and smaller. Soon you will no longer put together circuits out of individual components. It will all be tiny little "modules" for any function you need. Kids will laugh at Grandad when he talks about a single transistor in it's own package. Lol.

 

It is: (see PDF).
ADDED:

Standby current is 1...2uA (see PDF-2), so they ON/OFF LED only (pin "OUT").

Thanks for this.

 

Note that the M34 chip I linked to in post #3 and the datasheet @Danko posted is NOT your chip. The pinout is different and the M34 chip is limited to 2 or 3 LED, not a 5m string.