| T O P I C R E V I E W |
| georgecheng |
Posted - Nov 22 2008 : 10:07:24 PM
I found a time delay relay on this site (http://www.aaroncake.net/circuits/relaytim.asp), wonder anyone could advice me, how to calculate the time delay here.
Actually I looking to make a minute delay and wish to make it turn OFF once the circuit if OFF. Problem to change the circuit above to suit my useage?
On top of that, i also found another time delay (http://www.astron.nl/~smirnov/poweroff.gif), but i have tried to make it, but it fail. I simply can't get the 12v output from the transistor. Anyone could advice me? |
| 5 L A T E S T R E P L I E S (Newest First) |
| audioguru |
Posted - Mar 16 2009 : 9:09:29 PM
A 555 needs to have many huge expensive film capacitors in parallel to time for hours.
Use a CD4060 or CD4541 oscillator/divider instead. |
| r.setzu |
Posted - Mar 16 2009 : 12:51:58 PM
i need to have a delay time from 1 minute to 3 hour, p.e. using a lm555 component with a relay.
Power for the circuit around 5 to 12v tthe contact of delay around 2 amperes.
by
rsetzu |
| georgecheng |
Posted - Dec 01 2008 : 11:00:58 PM
Thanks everyone for the answer, i finally get everything in track and working.
By the way, is there any circuit that is able to auto off the cicuit once the switch is toggle on? THanks |
| audioguru |
Posted - Nov 23 2008 : 10:55:51 AM
The datasheet for the 555 timer IC has the formula to calculate the timing. But since the project uses a 10uF capacitor for up to 20 seconds then 60 seconds would use a capacitor with 3 times more capacitance, wouldn't it? Try 33uF.
The circuit you found has the D and S of the Mosfet shown connected backwards. The S should connect to ground. |
| Mr C |
Posted - Nov 23 2008 : 05:51:34 AM
Formula is 1.1*R1*C1 Answer in seconds |
