Electronics
Raymond Hodges | 26/12/2014 13:47:22 |
71 forum posts 1 photos | Hello there I know very little about electronics although i am able to read a circuit diagram, and solder components onto a PCB, but thats all. Q1 In a circuit a Bridge Rectifier is required (12v 2A), does it matter how big the Rectifier is so long as it is more than that required. Q2 How can i establish what type of a transformer i have not knowing the primery voltage or the output. Thank you Ray |
frank brown | 26/12/2014 14:15:45 |
436 forum posts 5 photos | A1, if the transformer is delivering X volts, then the voltage of the diodes must be 1.4 times X volts or greater. A2. Very difficult, the best way is to get a bit of low voltage AC, say 6V from a bell transformer and wire it to a low voltage winding (thick wires) and measure the input voltage from your bell transformer and the output voltage on the other windings. eg, voltage from bell transformer = 4V, voltage on windings, 17 V, and 80v. This would mean that the 80V winding was the mains (230V), the 17V would be 17/80 X 230 ~ 45V and the 4 V winding was actually 12V. The actual power depends on how hot the transformer can get. Best to compare with a known example. Frank |
John Haine | 26/12/2014 14:34:25 |
5563 forum posts 322 photos | Q1 basically no, as long as the diode breakdown voltage is as Frank says, bigger is fine. Q2 - that method is not recommended! If the low voltage winding you connected to was 4v say there would be 230 v on one of the other windings. Also it may not even be a mains transformer, could be an audio one. Frankly I suggest that you buy the transformer you need so you have a known quantity. You could post some photos of what you have? |
WALLACE | 26/12/2014 15:25:22 |
304 forum posts 17 photos | Don't forget there's going to be a 0.7v drop across each diode.... There's a very good freebie programme - Google 'PSU Designer'that can simulate simple power supply circuits. W. |
WALLACE | 26/12/2014 15:55:10 |
304 forum posts 17 photos | Wrt to 2 - someone with a bit of experience would get a fairly food idea on the type - and if a power tranny - the wattage or 'VA' just just by looking at it - a 50VA transformer for example, is pretty much the same size as any other 50VA one. The primary and secondary windings I would identify and quantify by using a meter and 'Variac' - that's probably a little too dangerous if you have limited experience with messing about with potentially lethal mains voltages. W. |
Les Jones 1 | 26/12/2014 16:10:24 |
2292 forum posts 159 photos | Hi Ray, A2 Les. |
Harold Hall 1 | 26/12/2014 18:58:18 |
418 forum posts 4 photos | Ray The following web pages deal with AC to AC and AC to DC conversion, the latter, particularly using a transformer, rectifier bridge and possibly an added smoothing capacitor. You may find this useful. **LINK** Harold |
Raymond Hodges | 26/12/2014 21:42:25 |
71 forum posts 1 photos | Well i am overwhelmed i didnt expect quite as much advice thank you all. The bridge rectifier required in the circuit is a 50v 4A, i have a 1000v 25A Bridge rectifier wold that work? I will take the advice from John Haine an Buy one. Your link Harold, i will try to understand it a bit more. Ray Edited By Raymond Hodges on 26/12/2014 21:43:02 |
Les Jones 1 | 26/12/2014 22:57:17 |
2292 forum posts 159 photos | Hi Ray, Les. |
Raymond Hodges | 27/12/2014 09:51:01 |
71 forum posts 1 photos | Thank you Les I am making a Spark eroder, or EDM, and i do have a lot of electronic bits and pieces which i am trying to understand a bit more about. I have built one as described by Mike Cox 1 on his web site, it works but very slow. At the moment i am gathering information on what works with what, trying to keep the whole thing as simple as posible. Ray |
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