555 Timer Help

Ant's picture


Joined: Dec 11, 2019

Replies: 0
555 Timer Help
December 11, 2019 - 3:55am

Hello all. So I'm a super beginner when it comes to electronics. I put together a solenoid timer from a design I found online. It works as it should, but I'd like to adjust the timing beyond what it can currently do and have no idea how to do so. This circuit opens and closes a solenoid that I use to inject CO2. With the potentiometer I can adjust how many times it opens and closes. What I want to be able to do is adjust how long the solenoid is open each time it opens. As it is now, its open for a fraction of a second. I've attached the schematic and board that I used to put it together. Any help would be greatly appreciated and remember I'm just a beginner so.........small words :)

Debasis Parida's picture


Joined: Aug 22, 2019

Replies: 120
Vary the Resistor and capacitor values
December 11, 2019 - 10:56pm

Hi Ant, you can control the freq of the output voltage  by varying the values of resistors and capacitors.You can refer the frequency formula to do this.For details check the below link.it will be helpful.


Sourav Gupta's picture


Joined: Feb 12, 2018

Replies: 198
Add a pot in series with the R1
December 11, 2019 - 11:36pm

Add an 1k pot in series with the R1
Short first two terminals left one and the middle one of the pot and connect it with the OPOT1. Connect the other pin with OPOT2. Hope this will work.