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| Building a Penny Pusher Arcade Game |
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| Bluechip:
--- Quote from: raynerd on August 02, 2013, 01:32:16 PM ---Used a few ATX supplies for various jobs over the years. They have a 5v line and 12v - do they have a 7?? If not, maybe this is terrible electronics but wont using the 5 and 12v lines give me a potential difference of 7v ?? :zap: --- End quote --- Yes it will, but it won't be 7V emf ... :thumbup: think about it ... A 12V supply pushing out current through a load to 0V A 5V supply doing the same ... ie out OK . as awemason rightly says most ATX's wont power up unless the 5V is loaded, often to about 1A. which means a 5R resistor. PSU :thumbup: now comes up OK ... Now connect your motor from +12 to +5 , the motor can now sink it's current through the 5R resistor Except it's start current will be ( modestly ) 3A which will try to drive the 5V O/P up to 15V. Well it won't get there 'cos it's only got 12V to start with. The 5V will not see the funny side of the joke, will sense over/voltage and shut the ATX down. You need to visit the difference between 'PD' and 'EMF' and 'sourcing' & 'sinking'. The 5V supply can only source 5V, the chances are it can't sink the 12V. Not while it's alive anyway ... You seem to be looking for the most abstruse solution you can devise to a non-problem :lol: AS Bill Todd, VTSteam et al have alluded .. Get a 0-6 0-6 50-ish VA transformer, nail it to a 15A bridge rectifier, switch on, slide off for a pint while you leave it to ekkle. Dave BC |
| vtsteam:
The one secret we haven't mentioned to Chris is.............. a 6V transformer when connected to a bridge rectifier will give you sommat more 'an 6 V DC. output. |
| vtsteam:
Here, a picture is worth a thousand words. This is for a simple transformer -- and according to Bluechip you can eliminate the capacitor as well. Or if using a center tapped transformer, you don't even need 4 diodes, or a full wave bridge package. Just two diodes (I believe, or is it 1?) The only problem with all of these, as you say Chris, is, they aren't adjustable. But if they're right, you're good to go |
| Bluechip:
Not if you omit the capacitor. It'll just see the rms . It will actually be a bit more than 6V rms with a 50VA tranny 'cos 50VA is a bit over-rated for the job. It will be up a tad because of the favourable load regulation. Not looked but I would guess the load regulation would be about 10% with a 50VA tranny .. :beer: time for me .... as one J Reeves once said 'I hear the sound of distant Becks' and I don't intend it to be distant much longer ... Dave BC |
| awemawson:
The simplest solution in my opinion is a suitable transformer, followed by a bridge rectifier and capacitor, followed by the pwm unit Chris has already bought. This way as he builds the penny pusher he can adjust the speed to suit. The speed will depend on the load and this will probably change as the design develops, so a fixed speed solution is not a good idea. Build a little 'post design design' into it for later tweaking ! |
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