||Toggle switch action to momentary switch action
using Opto couplers
The same idea can also be build with Opto-couplers, but requires some more components.
The Opto-coupler diode cannot be used as time-constant parameter, so some external resistors need to be added for the current limiting and time constant setting.
For toggle to momentary with one opto-coupler, the charge / discharge current needs to flow through the same opto-coupler. If you use a DC opto coupler, you can add a diode bridge, but this is component wise rather wasteful. Its simpler to use an AC type Opto-coupler, that has two diodes anti-parallel inside. (These types are often found in telephone equipment).
Toggle to momentary with single AC type Opto-coupler: This circuit gives an Opto-coupler ON time of about 60msec.
Toggle to momentary with two Opto-couplers for controlling different switches.