Here's a Crunch Captain Deluxe, I think could be easily modified to work, just delete the switch on the right
https://drill.taydakits.com/box-designs/new?public_key=QkZGaVR5SThsQ0ZEQVZsckZLTnhmdz09Cg==
Found the following on an Ebay Listing, it also compared them to a 1N4147.
Silicon pulse diodes.
All diodes are new(NOS) in sealed factory boxes,
taken from the surplus inventory.
Electrical parameters:
•Maximum DC reverse voltage: 30V;
•Maximum forward current: 20mA;
•Maximum working...