AUGUST, 1951
A SIMPLE ELECTRONIC RELAY JOHN J. PITHA Michigan State College, East Lansing, Michigan
THE
obvious disadvantages to the mechanical-type relay is apparent to everyone who has ever experienced the annoyance of "sticking," "chattering," or "sparking" that usually accompanies their operation. The electronic t,ype relay, with its absence of moving parts, is the answer to the problem of elimination of the abovementioned annoyances. Some thyratron control circuits are to be found in the literatureL. but for the most part these specify tubes of foreign manufacture, or a type no longer manufactured. Since there were no tube characteristics given, it is not easy to substitute available thyratron tubes. Visitors to these laboratories have expressed interest in the electronic relays they have seen in operation here, and for that reason it is thought. that the wiring diagram, along with a list of parts required for the relay might he of general interest. The list of parts required is given in the table, and the circuit diagram is given in the figure. The component parts of the apparatus need not be mounted in the cabinet suggested, but may be mounted on a board. If the relay is to be used in the vicinity of a constant temperature water bath, however, it probably will be desirable to enclose the entire electrical assembly. The only caution to he exercised in putting the component parts of the system together is to be certain t,hat the banana jacks are insulated from the metal cabinet. This caused some difficultly until the nature of the problem was realized. The G.E. Thyratron #3C23 was chosen because it was available surplus at very low cost, and had a power rating sufficientto do the job for which it was intended. This tube is rated a t 1000 volts and 1.5 amperes, but since the maximum current passed is never to exceed 1.5 amperes, the maximum load that can be controlled is 165 watts at 110 volts. I t has been found that a 125- or a 150-watt immersion heater will maintain the \'a"*,.
' SCHV-ENK, H. S., AND D. E. NOBLE,J.P ~ Y Scham., . 41,80+10 (1937).
IIOVA.~
Parts List for Thyratron Control Unit
$;R:. .:.:.:.:. :.100&0hm, ~ t , " d ~I-watt ~ ~ ~ ~resistor ~ n ~ ~ ~ , "BP3024 ~~,",","eI) -
.. .."eon panel-light a s e m b l ~
SW.. . . .D.P.S.T. Toggle switches (two)
Cabinet, with chamis, Bud #CUI99O Battery, 4.5 volt &Prong, type RS tube socket 2-Prong female receptacle with separate mounting plate %Prong male plug Banana plug8 and jacks ( t ~ pair) a
temperature of a normal size water bath up to a temperature Of about 30°C. with no difficulty. For higher temperatures, a second heater "on" all the time, used in conjunction with the controlled beater, gives satisfactory results. Of course it is possible to actuate a me, .- . ...- .......... in the ease of control again becomes the mechanical relay.
