The electronic clap undeniably originates from 70s funk and disco, as a recording technique used to accent a song in a different way to a snare drum. A clap is a very powerful sound, it normally has a dramatically higher volume than any other human made sound but only lasts a few milliseconds. It is normally not very dynamic and is hard to distinguish by itself ; a recording of a single clap can sound peculiar and can sound like any impact sound.
When a clap is performed in a reverberant room you can instantly hear all the resonant detail of the space and because the clap only lasts a few milliseconds, therefore it does not obstruct the texture of the rooms reverberant decay. Also when a small crowd of people clap at the same time the sound is far more distinguished and has a more powerful effect on the listener. The sound of a group of people clapping is very unique due to the slight timing differences caused by each individuals timing error. Not very many sounds are like this and therefore is very recognisable as a clap. Recording studios used tricks of multilayering people clapping and adding ambience either physically or by reverb to make the clapping sound good and prominent. see Loose Joints famous record for a natural handclap.
Now, I am not trying to say that clapping over recordings started in the 70’s, but this is when electronic instruments seem to have become more sophisticated and attempted to simulate this sound. I think the general aim was to make it easier to add claps to your recording without expensive equipment and large studios. In turn this mutated sound shaped the way music was constructed as producers could create unison claps on peculiar rhythms other than standard off-beats with in-human timing. Below being my favourite.
Design of an analogue hand clapper
The design of an analogue clap is very interesting, there is not a lot of variation, this leads me to believe that there is either some kind of shared paper that inspired these circuits or that most are clones of one single design. But basically an analog circuit models the sound by taking a trigger and treating it in different ways then mix the results back together. Generally the circuit is divided into 2 sections.
A filtered noise source fed into a amplifier controlled by a short decay - this simulates ambience
A cluster of impacts created by feeding the decay envelope into a chain of comparators - this simulates a cluster of claps
I have found each circuit has employed different tricks to make the sound more human in timing and some add different parameters you can use to control the timbre of the sound.