[GreenKeys] Transient voltage suppressers

[Jones, Douglas W]

Teletype Model 33s use several GE 20SP4B4 thyrectors as
transient voltage suppressers.  I note that they are
currently available on Ebay from s source I know nothing
about.  They claim more than 10 available.  A bit pricey,
but I haven't seen these available very frequently.

There are also a pair of these in my 1965 PDP-8, one
across the mercury relay coil, the other across the relay
contacts.

-- http://www.ebay.com/itm/121419976637

		Doug Jones
		jones at cs.uiowa.edu