sabahan
Newbie level 6
I uses a 10uF electrolytic capacitor on a bread boar to test the circuit,the diagram shows part of the circuit with act as a timer circuit when the opamp goes high,when voltage from the charging capacitor is fed to a OpAmp voltage follower,and to other part of the circuit.
when I use a electrolytic capacitor,the RC time constant is about 8 second and when I fabricate the circuit on a PCB and uses a SMD ceramic capacitor (Non polarized),the time constant drop to about 2 second.
I desolder the ceramic capcitor and put in a electrolytic capacitor into the PCB,the time constant work as design again which is 8 second,why this happened?
The discharge resistor is a 910K 1% metal film resistor
when I use a electrolytic capacitor,the RC time constant is about 8 second and when I fabricate the circuit on a PCB and uses a SMD ceramic capacitor (Non polarized),the time constant drop to about 2 second.
I desolder the ceramic capcitor and put in a electrolytic capacitor into the PCB,the time constant work as design again which is 8 second,why this happened?
The discharge resistor is a 910K 1% metal film resistor