A very common night light in the UK, that uses a 7W tungsten night light lamp being run half wave to give a dimmer output and long life. The circuit uses a thyristor to switch the lamp on when an LDR senses that it's dark. The thyristor is amazingly sensitive.
I think a better title would be "Autopsy of a murdered tungsten night light", lol
I tore one of those apart that quit working. It was even simpler than what you diagram there, no fuse, no diode, I'm guessing that the TO-92 packaged device must have been a very small triac? What I wanted (and got) out of it was the LDR, not much of anything else was worth salvaging. Then I lost the damn thing…
Took apart a similar 7W, night light and found a single resistor (red, black, green and gold) 2M ohms, an LDR and a single component with 3-legs, labeled PCR 606J that looks like a thyristor. I'm new to this side of electronics and have been getting confused with transistors, thyristors and SCR's.
Just bought a couple of these online. Hopefully arriving tomorrow.
I need something to light the downstairs hall at night so I don't have to wake everyone.
Have to admit, I always preferred the incandescent ones.
LED is too harsh of a cold white, where as the half run incandescent is a very warm orange glow.
I wonder if putting a small capacitor in parallel with the lamp would reduce the shimmering, as it's only half wave, and the current draw from a 7w lamp is low, an electrolytic might do the job nicely.
Hi Clive. At the start you use a UK plug adapter which you then remove to reveal a UK plug?! What am I missing here?
Those 7W bulbs are the same as some fridge ones……..I think poundland sold two for a quid.
I bought one of these for teardown/hacking too. Like you, I tried tri-wing screwdrivers with no success. I even bought some stripped screw/nut extractors and I still couldn't move the screws.
Keep the fuse for use in a multimeter, it will survive the blast.
This circuit explains why most LED bulbs say they are unsuitable for night lights, as half the waveform cannot cycle the current back and forth through the capacitor in LED bulbs using a capacitive dropper circuit.
Wow, the MCR100-8 is rated as 40uA typical (200uA max) "Gate Trigger Current", so the 8.2M resistor seems marginal.
these pretty poor bulbs even run at half power last only around 500 hours, not spectacular, as you say, better off with the led versions, which in my experience last around 10k hours (i have had loads of night lights over the years running all night!)