Hank102938
New Member
You may have seen my previous post regarding the Power supply I'm working on. I've thought about it and have decided it wasn't a lost cause... So now I've been trying to come up with a design that will work with the parts I have already bought. My transformer has a center tap on it which will give me 12.5 V or so at a maximum of 3A (the fuse will blow with any more... I think)
So here is my new design:
**broken link removed**
I'm don't know much more about AC other than it alternates in a sine wave pattern... So, will this work. My idea is, is that a DPDT switch will select the 25V or the 12V transformer output and the corresponding resistor needed to get the correct voltage range.
First, will my idea of using the center tap(12V)/normal(25V) selector work to get 2 different input voltages to the rectifier. And how much will my capacitor up the voltage. Something I read about the center tap being 180 degrees out of phase... I don't really know what that means or how that would effect my design. Even if it would not work, can I buy some type of transformer with two different output voltages? Something someone suggested in my previous thread.
Second, will my idea of using the DPDT switch to select the voltage and the corresponding resistor work?
Third, output amperage? This was the problem in my first design. There was too much voltage dropped at 1.5A when the regulator was set to 1.5 volts that the heat coming off the regulator was not practical to try and dissipate with any heat sink. So, I'm thinking that 1A or 0.75A is all I would need. So, how would I create such limitation? Where would I need resistors, what resistance, what wattage rating. Also, how do I calculate those for future reference?
Just as a side question, how would I make the output amperage variable?
So here is my new design:
**broken link removed**
I'm don't know much more about AC other than it alternates in a sine wave pattern... So, will this work. My idea is, is that a DPDT switch will select the 25V or the 12V transformer output and the corresponding resistor needed to get the correct voltage range.
First, will my idea of using the center tap(12V)/normal(25V) selector work to get 2 different input voltages to the rectifier. And how much will my capacitor up the voltage. Something I read about the center tap being 180 degrees out of phase... I don't really know what that means or how that would effect my design. Even if it would not work, can I buy some type of transformer with two different output voltages? Something someone suggested in my previous thread.
Second, will my idea of using the DPDT switch to select the voltage and the corresponding resistor work?
Third, output amperage? This was the problem in my first design. There was too much voltage dropped at 1.5A when the regulator was set to 1.5 volts that the heat coming off the regulator was not practical to try and dissipate with any heat sink. So, I'm thinking that 1A or 0.75A is all I would need. So, how would I create such limitation? Where would I need resistors, what resistance, what wattage rating. Also, how do I calculate those for future reference?
Just as a side question, how would I make the output amperage variable?