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Series 40 Reed Relays - Unique? The design of this reed relay series goes back several decades when it was invented by the Founder of Electronic Applications Company. It featured the ability to wind coils directly upon the glass body of the reed switch obviating the need for a real bobbin to be used for the coil. Special, easily made tooling was devised to form and apply a cap of very high insulation resistance (1x10 >12th ohm) cured polyester on each end of the reed switch. On one cap end two extra leads were molded along with the switch resulting in a psuedo bobbin of glass capped on each end with this hard plastic, one holding leads to attach small #42 or similar size coil wire and wrap it around the bobbin and attach the other end to the other cap lead. We estimate that well over 80 million reed relays were made using this construction. Extensive temperature testing over the years proved that this design to be of a most viable construction.

It was a novel, ground-breaking no bobbin concept by Mr. Walter Podolece of Electronc Applications Company fame. He thought up the procedures necessary for creating a virtual bobbin reed relay. He had received an rfq to supply over $100,000.00 of special relays to a rather large company. He responded to the rfq and received about half of the order to be delivered in a tight time frame with penalties for late delivery. In those days that kind of money was a very large contract when adjusted to inflation. Unfortunately, he could not buy the necessary plastic bobbins due to a time constraint from the bobbin manufacturer. He had borrowed the funds for their purchase, and a relay shipping deadline was closing, as was the need to make payments on the loan. An old saying exists -  necessity leads to invention, and the rest of this story is reed relay fantasy come true. He devised this unique assembly system wherein there was no direct plastic bobbin in which to insert the reed switch. The virtual reed relay bobbin came into being. He invented the remarkable techniques by which a coil wire could be wound directly on to the body of the glass reed switch. It turned out that winding wire directly on the reed switch glass tube provided higher coil efficiency. This allowed very sensititve relays to be manufactured that up to that time could not be done and had been deemed to be impossible. The finished, wound, coil /switch assembly was then inserted into a cold rolled hard drawn steel tube that had been annealed and nickel plated. Each end of the relay was filled, resulting in a hermetic seal at each end. The material used was a polyester formulation of his design. What resulted was a relay that was near to impossible to destruct and by design provided a near perfect magnetic shield allowing the relay to be mounted next to another magnetic field generator with impunity. 

The rest is a 40 year history with the largest variety of super reliable, tubular reed relays ever designed and then made available to the buying public. Uncounted 10's of millions of these relays have been sold over the last 40 years and maybe even longer, with no known reported physical structure failures of the relay. Even the DIP reed relay designers became aware of his success and developed their own free form coils with no bobbin, just slipping the finished bobbinless coil over the switch, then using a super glue to hold it in place. Soldering of the coil leads to the lead frame just prior to molding the relay was the last step of the process. It is a tribute to the success of the design that others in our industry later copied variations of it to their own DIP and SIP reed relay products. A patent application was prepared on the process, but history has dulled it's whereabouts


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