10v AC to DC?

I am replacing a board & 5 digit LCD display with a new 5 digit LED display

The power feeding the display is 10v AC. The new display takes 10v DC and draws about 0.0512 amps.

Can I use 4 diodes to convert the AC (60hz) to DC ? Something like the attached?


Think you need to show what you had and what you want to do. Those ac seven segment use a driver chip that I more then sure will not work with leds

Can't tell which your "+" symbol refers to but that should be the top lead. In addition you need a filter capacitor, 20 to 100 uF or so should be ok at the output of your rectifier bridge and a 10 volt regulator. Your rectified 10 volts will have peak value of 14.14 volts so it needs to be brought down to 10 V with the regulator.

Basically yes but you'll need a bit more than a simple bridge rectifier

10V AC will, when rectified and smoothed , give you around 14 volts under no-load

So first you'll need a decent smoothing capacitor and ideally a voltage regulator to give you the 10 volts DC that you need, something like an LM317

As stated by others, you have the + and - symbols transposed on the DC side

You have the output polarity wrong, the +V is at the union of the two cathodes and the -V is at the union of the two anodes.

I'm sure the op has a vfd and not a LCD and I don't think there's a drop in replacement with leds and four diodes

regarding the transposed on teh image -- I slapped that together in haste and didn't notice... but thank you for pointing it out and moving beyond that flaw...

thank you! I have the cap & voltage regulator here, so in that regard, I guess I'm lucky.

I breadboarded it and you are right -- I actually got a peak of 14.3 volts -- can I ask why it increases? I expected that, with the diodes, it would have decreased.

Capacitor & regulator smoothed it all out and is now a nice clean 10v & the whole thing is working as it should be.

Thank you!

The number in 10 volts AC is an average of the sine wave. The top of that sine wave is higher (i think it was something like the square root of 2 which comes pretty close to your result). After rectifying and filtering it, you'll see a voltage close to that number if there is no load.

MAS3: The number in 10 volts AC is an average of the sine wave.

Actually it is the RMS value, not the average. The peak of a sinusoidal voltage is root2 times the RMS value ie 1.414 x 10

With no load attached and a smoothing capacitor the outputs of the diodes is the peak value. With no current flowing through the diodes there is no voltage drop across them.

Since your measured DC output was quoted as 14.3V DC it is evident that the AC voltage is somewhat higher than 10V AC

Ah, yes, the average is zero so that doesn't tell a lot. :blush:

Thank you for the explanations!

But it remains you have not explained what the displays in concern are, so you are most unlikely to get particularly helpful information. What you need to do is to provide perfectly focused pictures (and preferably not as an attachment but links to a reputable lodging site) or links to the devices.

And when I say "particularly helpful information", I mean in order to do it efficiently.

I got very helpful information.

"Dead module was powered by 10v A/C" "replacement module wants 10v D/C" "Can I easily convert 10v a/c to d/c?" Answer "Yes, but you'll want a capacitor and voltage regulator in addition to the diodes" .... and I learned why 10v a/c with diodes to make 'dc' results in 14v not 10 --

I actually think providing more info would result in less helpful information, as, no doubt, "We need schematics" "Where's a data sheet?", when "can I convert 10v a/c to d/c easily?" got me an answer that was helpful & I learned a few things...

The fact that the old module was an lcd and new is an led seems superfluous, as the only single bit that I needed help with was getting 10v d/c out of 10v a/c...

I realize you probably are concerned about minor details at the moment but for future reference INPUTS are generally shown on LEFT side of page (or screen) and OUTPUTS are shown on RIGHT side of page (or screen). This has been the convention for electronic schematics since the beginning.

The reason for the difference in AC and DC voltages is that if you attached a resistor load, the resistor would get just as hot if both were the same voltage in AC rms and DC. In the early days, people were worry about power delivered and not what would happen if I added diodes. That is where the square root of 2 comes in.

re: convensions: Thanks for pointing that out. I had no idea. Will remember that for next time.