i have a transformer from smps,how do i use it????? - Page 1
Forum section: electronics / beginners

author: saipavan
author_rank: Contributor
timestamp: August 27, 2013, 03:14:14 pm
content: i have got a transformer from an old power supply unit of computer. it has got a label named "JYD ER-35E".can i know how to use it???

author: c4757p
author_rank: Super Contributor
timestamp: August 27, 2013, 03:38:00 pm
content: It's a custom SMPS transformer, it's unlikely to be useful outside its intended purpose. I'd probably "use" it either as a weight to hold down my trash bag, or by cutting off the windings and winding a new transformer around the core...

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 27, 2013, 04:31:15 pm
content: How was that thing connected originally? If the primary side was connected to mains then you might actually have something useful. Some SMPSs will just rectify mains and boost/buck that. But that might be something more specialized, like a flyback transformer.

author: Paul Price
author_rank: Super Contributor
timestamp: August 27, 2013, 04:42:56 pm
content: Use it to make a nice bench power supply. See attached.You need to identify the HV side winding, it will be a single winding while the output secondaries will likely have taps and the wire size is much smaller, also the HV side will have smaller size wiring visible at the terminals. There even should be a winding that is used to power ULN284x type devices after it has been started up(where D3 is connected in the attached.)You might also google "Tiny Switcher" for an inexpensive single 8-pin dip controller that uses a simple circuit with very few parts to deliver up to 40W.Just because it is meant to used off-line 120/240 VAC doesn't mean it wont work with you to experiment with it using your bench supply. If you find a wallwart or a laptop power supply to give you 12V to 20V, you can discover the possibilities of this transformer and the purpose and pinout of all its windings. Of course, if you have the board you've pulled this from the pinout would be obvious.You could also use one of the secondary windings as a combo transformer/inductor with a buck switching regulator such as LM2576 LM2678 etc and you could obtain isolated higher or lower voltages from the other taps.The only limitation if your imagination.

author: Zero999
author_rank: Super Contributor
timestamp: August 27, 2013, 05:46:19 pm
content: The core seems like a standard part. Of course you need to determine the winding or re-wind it for it to be any use.http://www.epcos.com/inf/80/db/fer_07/er_35_20_11.pdf

author: Paul Price
author_rank: Super Contributor
timestamp: August 27, 2013, 05:55:37 pm
content: The windings as they are might be just fine for you, you can verify this by experimentation.Life is too short to sit around unwinding and rewinding small flyback transformers.You could apply an AC signal to a winding from a function generator or else pulse one of the windings just using a 555 timer and a driver transistor and clamp diode to see what a given pulse on one winding transforms to the polarity and magnitude on the other windings. It is certainly worthwhile to try this is you want to learn about electronics and switching power supplies.

author: saipavan
author_rank: Contributor
timestamp: August 28, 2013, 04:07:32 am
content: the winding which has 2 pins is connected to the high voltage.first the high voltage is rectified and hen supplied to the transformer.can i use it to power a lm317??

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 28, 2013, 06:02:59 am
content: If the mains is rectified before the transformer then this is likely some kind of flyback or forward conversion topology. Which means the transformer is meant to run at much higher frequencies then mains frequencies. You won't be able to hook the transformer directly to mains and use an LM317.

author: dr_p
author_rank: Frequent Contributor
timestamp: August 28, 2013, 06:35:44 am
content: Quote from: TerminalJack505 on August 28, 2013, 06:02:59 am+1

author: Zero999
author_rank: Super Contributor
timestamp: August 28, 2013, 12:53:12 pm
content: Quote from: saipavan on August 28, 2013, 04:07:32 amNo it's a high frequency transformer.The mains is rectified to DC which is then converted to high frequency AC, is supplied to the transformer and converted back to DC.Although there are more steps in the conversion, it works out more efficient because high frequency transformers are more efficient and PWM is used to regulate the voltage, rather than a linear regulator such as the LM317 which wastes excess power in heat.