Build Your Own Clone Message Board

One of the things I just did that has made thing easier to test is to whip up a power supply filter and voltage divider on a very small bit of vero board. I used to do those functions on each breadboard, but it's the kind of thing that lends itself to a fixed bit of kit to save time and hassle.

If you want to play around with op amp circuits, this bad boy is very helpful.

Obviously, you could tune these values to taste or requirement.

I soldered mine directly to the 9v jack to save the extra mess of wires.

The left side connections are straight from the DC jack. The right side connections are:

9v out = filtered power at 9v
4.5v out = vref for op amps (also filtered)
GND out = this pad is for ground supply if you solder the DC jack to the board

Note the cut under the 47R resistor. (You could use 100R instead)





Here's the one I built:

Don't forget to filter your Vref!

Damn, wrong forum. Could a mod please move this to the Schematic/Layout forum? Thanks


Damn again! Maybe I'll just add another cap. There's room.

Moved. This is very cool CJ. Are you going to update it, or is it already?

Just fixed it.

Thanks.

It's 47R.

It helps to reduce noise from the power supply. It can be left out. If you want to leave it out, don't cut the trace in the first row.

In many cases, that resistor will have no noticeable effect. But sometimes it does, so it's best to include it if you're building this little gadget.

It's just that at such small values, you get the filtering without significantly dropping the voltage at the output. 100R is a more common value, and it is often used in power supply filters. But I've seen 47R as well (the Rat uses it), and I had them on hand, so.....

Thanks, CJ. I feel like I should be putting an apple on your desk or something.

Let me expand a bit.

My own experience is that the filtering resistor, if has a noticeable effect on noise it is with op amp circuits. It doesn't seem to have any effect on transistor-only circuits.

So what would this look like if you didn't need the 4.5v vref?

Take out the two 100K resistors and C2.

So the caps should be rated 25V, or at least 18V, and they are smoothing ripple. I am still wrapping my head around polarized/non-polarized cap applications, and making a fool of myself here really helps!!