Trip Points either voltage or current levels to trip a comparator

[audioguru]

Atually, the capacitor charges to about 12.7V because as it charges then the current from the output of the NOR gate drops to zero allowing its output voltage to reach Vcc which is +13V. The very low or no current in the diode allows its voltage drop to be only 0.3V so the capacitor charges to about +12.7V.

But the actual peak voltage of the capacitor does not matter because it is much higher than the threshold voltage of the opamp it feeds.

 

[Billy Mayo]

So what is the reason for the peak detector diode? is it to shorten the charging time?

 

[audioguru]

The diode allows the charging time of the capacitor to be fairly short and the discharging time to be 57.6 times longer than the charging time. (576k/10k= 57.6 times longer).

 

[Billy Mayo]

The diode allows the charging time of the capacitor to be fairly short and the discharging time to be 57.6 times longer than the charging time. (576k/10k= 57.6 times longer).

Yes I get it , thanks

Any reason why they want the discharge time to be long and not short? I would think to make the discharge time short if you want the RC time delay to delay time to the full delay time

If the cap is not discharged fully or discharged half way and gets charged again, the time delay is cut in half , more or less