simple timer needed please help

[stephen-7486]

i need some help with with a timer circuit that will hold the output high for about 30 seconds when power is applied and then go low indefinetly until it is powered down and turned on again

 

[thannara123]

use monostable circuit .search threads in this forum you will get . Regards

 

[sherazi]

you can use 555 in monostable mode, use the timing resistors to select 30s, when there is a signal on the input pin the output will be high for 30s and then low again until again gets a signal,

you can input a pulse and the circuit would output high for 30 secs

for the resistor and capacitor values for timing u can use the program available here


go through this it will help

 

[kak111]

Here is one circuit.........................

You can use 4001 or 4011 cmos gates or 4049 inverters etc.
for faster output switching time add 2 additional gates serially to signal
without transistor and relay , output is over C2.
Output is logic 1 at start
Inverting output connect one inverting gate more.

**broken link removed**

Regards KAK