Momentary latching relay 2011-12-29

Just for fun I designed and built this simple circuit which drives a monostable relay by a singol momentary button.
Supplied by 24VDC the circuit works for a 12V-140 ohm coil. The relay should feature a time response of 5 milliseconds or less.

Components
R1 -470ohm
R2 - 22Kohm
R3 - 180ohm - 3W
R4 - 150ohm -3W
C - 470uF
K - relay coil - 12VDC -140ohm - 3 milliseconds


[video=youtube;0tR5nwfENb4] ...

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This is an improved version of the first one, which used two relay contacts.
When the button is pressed the relay coil takes about 2,5 Volt (half voltage). By releasing button the coil takes full votage and the Q2 transistor is supplied for a bit by the capacitor, so the relay turns on. By pressing button again the transistor Q1 is supplied and turns down the other one (through contact 11-14).
The relay coil is still energized (at 2,5 Volts) through the collector of Q1...

Click to expand...