I'm ok with fixing and adapting circuits but not so good with design. I've come up with an electronic switch circuit but I think it could use improvement. The goal is to turn on a 12v relay with a switch that is closed when off and open when on. The switch also has to have one leg grounded. It's a pressure switch with a single terminal. I also want the relay to stay closed (on) for a couple minutes when the switch goes from on (open) to off (closed). Here's what I've got now and it does work. But I had to use a pretty big capacitor and I'm still only getting about a minute of delay when going to the off state. Because I can't make the 10k resistor any bigger. I'm thinking that it is likely possible to get a longer delay and do it with a smaller capacitor if I was better at designing this. The other flaw is that this slowly lowers the voltage to the relay until it drops. The relay stays pulled to about 3 to 4 volts. I also suspect there is a better way to keep it fully on until the rc timer expires. Thanks in advance for any suggestions :-)
- posted
15 years ago