Was messing around today, just being curious. I made a circuit where an 08M2 was powered by 3.5V, through a 10ohm resistor and diode, with a capacitor on the PICAXE side of the diode, so when power is removed, the capacitor charge keeps the PICAXE going for a couple of seconds. The PICAXE can register the power removed as an input.
I was playing around with different capacitors, and I noticed something odd. When using two 6.3V 330uF tantalum caps, for a total of 660uF, the circuit would keep running for roughly 2 seconds.
When I switched to four 6.3V 220uF ceramic capacitors, for a total of 880uF, the same PICAXE circuit would run for roughly 1 second. When I added two more, for a total of 1320uF, it finally ran for roughly 2 seconds.
I am purely curious, why does it seem to take twice as much ceramic capacitance being used as an energy store to run a PICAXE, than tantalum? I tried looking into this, but all the information I can find comparing these caps is mostly related to frequency/leakage/temperature. The only thing I found is that ceramics generally have much lower ESR than tantalum, but it increases at lower frequencies. Could it be that at the ceramic ESR becomes very large at no/low frequency (energy store mode)?
I was playing around with different capacitors, and I noticed something odd. When using two 6.3V 330uF tantalum caps, for a total of 660uF, the circuit would keep running for roughly 2 seconds.
When I switched to four 6.3V 220uF ceramic capacitors, for a total of 880uF, the same PICAXE circuit would run for roughly 1 second. When I added two more, for a total of 1320uF, it finally ran for roughly 2 seconds.
I am purely curious, why does it seem to take twice as much ceramic capacitance being used as an energy store to run a PICAXE, than tantalum? I tried looking into this, but all the information I can find comparing these caps is mostly related to frequency/leakage/temperature. The only thing I found is that ceramics generally have much lower ESR than tantalum, but it increases at lower frequencies. Could it be that at the ceramic ESR becomes very large at no/low frequency (energy store mode)?