Time delay relay circuit?

Using Arduino General Electronics
1

Hello, I am trying to get a time delayed relay circuit working. I almost have it working, but just cant figure out one part.

To keep things simple, I am just working with a source voltage of 19v, a relay (220 ohm coil I think), a capacitor of 3300ufd and a resistor of 10k.

If I wire the +19v to the resistor, series to the + of the capacitor, then the - of the capacitor to ground, I have my desired effect. I get a voltage across the capacitor pins that ramps up over several seconds. It's this circuit: RC time constant / voltage calcultor

The problem is, when I connect the relay across the capacitor, it does not ramp up (or very little). It's as if the relay is draining, or maybe it's the resistance.

I am not sure how to account for this, am hoping someone can help, thanks.

2

Hint. A relay is certainly a discharge path... this is where you need to insert a device that will not try to discharge the cap faster than you can charge it... you need to replace the low impedance load with a high impedance load. A semiconductor or IC could help with that.

http://www.talkingelectronics.com/projects/200TrCcts/101-200TrCcts.html#16AB

3

So it looks like the key is the transistor, which looks like it cuts off the relay, until enough voltage builds up to trigger the transistor to flow, correct?

In each, I see there is a diode across the relay. Is that protective, or is that contributing to the delay function?