110V to 5V Module? - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: July 06, 2017, 02:24:27 am
content: Time's up!I retrieved this module from a Brother MFP printer and I suspect it will take 110V AC on the white connector and output 5V. I started to draw a schematic but got lost. The transistors are marked 667 and show as 120V 1A npn transistors. Am I on the right track? If it is what I suspect I would use it to power a couple of small 5V fans in a power supply I'm building.

author: floobydust
author_rank: Super Contributor
timestamp: July 06, 2017, 05:51:14 am
content: I see that board as a TDK high-voltage DC-AC inverter for CCFL backlighting. Not a 110VAC to 5VDC power supply.They take in 5 or 12VDC and output 900-1500VAC at several mA. Enough to give you a nasty shock.Probably a custom build for the printer display? TDK TAD376 has no search hits.http://www.mouser.com/catalog/catalogusd/645/2476.pdf

author: Zero999
author_rank: Super Contributor
timestamp: July 06, 2017, 08:26:10 am
content: Yes, it looks like a CCFL inverter. Going from what you've already reverse engineered and the picture of the board, it looks like a Royer converter circuit.With regards to safety: the output frequency will be above 20kHz and will give you a burn more than a shock and the current will be limited to a non-lethal level.

author: metrologist
author_rank: Super Contributor
timestamp: July 06, 2017, 12:04:34 pm
content: Oh, well now I must find a use for it.I was working on the schematic a bit more and then went to feeding a signal from my sig gen at around 5V, I guess on the output side

author: rsjsouza
author_rank: Super Contributor
timestamp: July 06, 2017, 12:12:32 pm
content: The previous comments are correct. One detail that detracts from your original assumption is that one of the poles of the white connector is directly tied to the negative output - if this was a mains power supply, one of the poles would be directly exposed to the low voltage section. Another giveaway is that the transformer construction is very inadequate for direct mains (50~60Hz) connection - usually at these frequencies the magnetic coupling requires a lot more wire and core material (and not ferrite as its core).

author: Yansi
author_rank: Super Contributor
timestamp: July 06, 2017, 12:28:21 pm
content: D667 = 2SD667http://www.redrok.com/NPN_2SD667_80V_1.0A_0.9W_Hfe160_TO-92MOD.pdf

author: rsjsouza
author_rank: Super Contributor
timestamp: July 06, 2017, 02:54:27 pm
content: Quote from: metrologist on July 06, 2017, 12:04:34 pmWell, if anything, just be glad you did not use the module in the correct way with your oscilloscope plugged on the HV output - the oscilloscope wouldn't be happy with that.

author: Zero999
author_rank: Super Contributor
timestamp: July 06, 2017, 03:26:02 pm
content: Quote from: metrologist on July 06, 2017, 12:04:34 pmYou appear to have got the taps wrong. The centre tap should go to the positive supply, via the inductor and it's likely the transistors' bases are driven from a separate winding. Plenty of schematics can be found by entering Royer converter into a search engine.

author: metrologist
author_rank: Super Contributor
timestamp: July 06, 2017, 06:39:37 pm
content: I removed the images so as not to confuse someone in the future, since they are wrong.

author: stj
author_rank: Super Contributor
timestamp: July 06, 2017, 06:58:25 pm
content: i just use usb chargers from discount stores.if your in the u.k. - poundland ones are good ( "BigClive" does teardowns on poundland stuff on utube)otherwise - inspect them before you trust them!!!!