 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Electronics : transformer
| Author | Message | ||||
| irishron40 Senior Member  Joined: 22/09/2014 Location: IrelandPosts: 251 |
i am wondering about two transformers i have one is from an old car battery charger It measured 12 vdc at the rectifier my rewind transformer from microwave measures 17.2 vdc at rectifier will this be the max voltage I can get? or would it go up after i connected my veroboard with capacitors? I did notice that when i connect a window wiper motor rated 12v 2.5 amp that the voltage when from 17.2 to 21 volts. that is what made me think would voltage go up after the veroboard with capacitors and transistors thanks ron |
||||
Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Without a capacitor on the output of the rectifier, the DC reading will be false. The rectifier output is not clean DC, its actually swinging between 0 and full volts 100 times a second, and the poor old multimeter is having a hard time trying to give you a sensible reading. With a cap across the rectifier output, the DC is filtered and will give a correct reading. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
and would it be much higher glen then what i read now from both transformers? im just wondering which transformer to use for my variable power supply thanks ron |
||||
| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Dont know. Remember, the reading was false. Gibberish, rubbish, has no significance at all, and should be discarded, forgotten and never used for any future reference. Put a cap on the rectifier output, and measure again. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
I did put a cap across dc output from rectifier glenn. cap I used was 28 v 3300 uf its exploded and smoke came out. maybe voltage from transformers are higher then the 28 volt? or would the uf be to low? one transformer has ac output of 12.9 vac and the other 19.5vac how do i know what size cappacitor to use? i did order 2 50volt 4700uf capacitors. but dont wanna blow those either. ron |
||||
| Pete Locke Senior Member Joined: 26/06/2013 Location: New ZealandPosts: 181 |
12.9VAC will give you near as damn it 18VDC and the 19.5VAC is 27.5VDC. If you cap went bang it was either faulty, or more likely connected in reverse to the rectifier. Electrolytic cap's are polarity conscious. Put them on backwards and they do make good smoke bombs  . |
||||
| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
thx pete , you are right.i blame it on my eyeside lol i didnt see the + on the dc output of the rectifier. so more then likely I had it reversed so would the two 50v 4700uf caps be fine? havent made up mind yet wich transformer to use. I do know that the small transformer outputs 11 amp. maybe that is plenty for what I need it for its a kbpc2502 I am using. its rated for 25 amp. sorry for being a pain. but I have to learn someway . thx for your patience with me. ron |
||||
| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
how can I reduce vibration on metal housing caused by the transformer leaking of the magnetic field vibration starts the moment I slowly lower transformer in casing without being in contact with casing. did anyone have this problem before and is there a way to reduce it as I wanna use this casing. thx |
||||
| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Most transforms buzz to some extent. Have you tried bolting it in place and see if the noise is still there? The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
yes.it doesnt buzzor vibrates, but the moment i lower it slowly into metal casing it starts vibrating withouth it being in contact with housing. Imsure its needs better shielding so it wont loses magnatic field. just wondering insted of varnish could I use resin, that will get rock solid. have some left over from my fibre glass boat. ron |
||||
| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Bolt it in place and see how it sounds. A microwave oven transformer is bound to buzz a bit. Ever heard a silent microwave oven? I wouldn't worry too much about it, but it may check to see its not loaded too much, by either a shorted turn on the secondary, or the magnet path. Without anything connected to the transformers output, power it up for a 10 minutes, then turn the power off ( and unplug the power lead to be safe ) and then put your hand on it. It's ok if it gets warm, but not too warm or hot. If its hot, then something is wrong. Also, not a good idea to handle the transformer while its powered. Bad bad idea. Very bad! The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
i used varnish glen and it doesnt buzz. only if it is near metal, even without being in contact with it. so it is defanatly leaking magnatic field from the core. just wonder how to reduce that. just wonder if i pour fibre glass resin on it would that seal it from leaking magnatic field. ron |
||||
 Print this page |
