I'm A Noob

[tony3d]

Ok want to make sure i'm right here. I take the arrows are pointing to the negative end of the capacitor on the right end correct? Really hate being a noob.

[rdl]

Yes, because the symbol in the stripe is a negative sign (-). Be careful because sometimes the stripe will point to positive, then it will have a (+) marking.

[c4757p]

Haha... I see axial electrolytics so rarely, I have to look twice too...

[madires]

... and the positive side got the groove.

[tony3d]

... and the positive side got the groove.

I guess the positive side of this one has a hole.

[tony3d]

Thanks for the help everyone. I successfully transposed this from all alligator clips to my breadboard, and it oscillates between the two LEDS just fine, but can someone explain why my power supply jumps between Constant Current, and Constant Voltage with each relay flip of the relay? I can also hear the transformer in the supply flipping between two taps.

[Dave]

When the relay state flips, the large capacitor gets connected to the supply rail. Because of the large capacitance and low ESR, it acts almost like a short (for a brief moment) and pulls a very large current from the power supply. The supply can't handle the current, so it momentarily switches to CC until the capacitor is charged up again. Simple as that.

[Paul Price]

Be careful, some tantalum through-hole mounted capacitors and many types of surface-mount ceramic electrolytic caps have only a stripe that indicates the positive terminal of a capacitor.

[tony3d]

Be careful, some tantalum through-hole mounted capacitors and many types of surface-mount ceramic electrolytic caps have only a stripe that indicates the positive terminal of a capacitor.

This one is indicated as (-). Thanks for the heads up!

[tony3d]

When the relay state flips, the large capacitor gets connected to the supply rail. Because of the large capacitance and low ESR, it acts almost like a short (for a brief moment) and pulls a very large current from the power supply. The supply can't handle the current, so it momentarily switches to CC until the capacitor is charged up again. Simple as that.

Thanks for the explanation. Would raising the current setting of the supply keep it in Constant Voltage then?

[Dave]

I think raising the current limit would just shorten the amount of time the power supply is in CC mode. The ESR of these types of caps is usually really low, so you would need a very beefy power supply to handle that current spike without twitching at all.

You could try adding bulk capacitance to the supply line or add a resistor in series with your capacitor, to increase the effective ESR, which in term limits the amplitude of the current spike. Try using something from 4.7 to 10 ohms.

[tony3d]

I think raising the current limit would just shorten the amount of time the power supply is in CC mode. The ESR of these types of caps is usually really low, so you would need a very beefy power supply to handle that current spike without twitching at all.

You could try adding bulk capacitance to the supply line or add a resistor in series with your capacitor, to increase the effective ESR, which in term limits the amplitude of the current spike. Try using something from 4.7 to 10 ohms.

Thanks Dave I'll look into ESR a bit more. I'm having a blast with this stuff so far. I use be a CNC programmer/machinist. Loved to trouble shoot jobs, probably why I like this so much. Now I do 3D modeling and animation working out of my house for the past 15 years. This is a nice diversion.