I designed this relay circuit to function as a DPDT
toggle which is controlled by a momentary switch. I strive to keep my
circuits simple with little or no integration (555’s, transistors, etc).
The circuit is shown active or “on” mode.
Half of RL1 and RL2 manipulate the switching and the other is
connected to an application. Relays are 200 ohms above ground and at one
point are referenced to positive that turns them off.
RL1 (which is off) applies plus voltage from its armature and
latches RL2 “on”. The application terminals are set to [A]. The
condition changes when S1 is activated, voltage is applied to RL2
latching RL1 “on” releasing S1 turns RL2 “off”. RL2’s armature is then
directed to R1. Terminals are set to [B].
When S1 is pressed again, the relays negative side are referenced to
positive, RL1 turns “off” (there’s no current flow). RL2 turns “on”
when S1 is released, terminals are set to [A]. There is slight lag
between relays depending on how long S1 is held.
If different relays are used, adjustment of R1’s value may be required. For example, OEG
relays (12vdc, 270 ohm coil) need R1 at 60 – 70 ohms. The prime
motivation for this design was to avoid using toggle switches for my
audio control panel. Another plus, it can be controlled from a remote
transmitted pulse. Relays are available at allelectronics.com
Author: Roland Segers