# Anyone Know about 555 timers!?

Discussion in 'General Discussion' started by Oracle, 13 Apr 2006.

1. Oracle

# Posts: 1,971

I'm looking for a schematic that would show a 555 timer energising a relay for a period of two seconds every 10 seconds using a capacitor rated at 10 micorfarads.

I'm aware of all the relevant pins on an IC 555 chip but could just do with some help locating a diagram of this...

It would also be handy if one terminal of the relay coil is connected to 15v DC

Thanks

2. PikeyPriest

# Posts: 1,186

T = 0.7 × (R1 + 2R2) × C1
and f= 1.4/(R1 + 2R2) × C1

T = time period in seconds (s)
f = frequency in hertz (Hz)
R1 = resistance in ohms (ohm)
R2 = resistance in ohms (ohm)
C1 = capacitance in farads (F)

Mark time (output on): Tm = 0.7 × (R1 + R2) × C1
Space time (output off): Ts = 0.7 × R2 × C1

Put in the capacitor values and play around with what resistances can give you those times.

Diagrams of the circuit your looking for are on:
http://www.kpsec.freeuk.com/555timer.htm#astable

Look for the 555 Astable design and just above it on how to hook the relay up

From what i remember the relay can switch absolutely anything its rated for as part of a seperate circuit.

3. Goliath

4. Oracle

Gangsta!!

5. Oracle