5 replies to this topic

[Old Bob]

A couple of years ago I bought a batch of new 5 pin relays (I was sure they would come in useful sometime!) They are marked 30/40A 14VDC with what I think is the trigger voltage - an oblong box with a diagonal line through it? - marked 12V. The pin numbers are: 87, 87a, 86, 85 and 30.

Question is, can I use these as simple 4 pin relays for fog and spotlights, heated windscreen etc?

Advice appreciated.

Bob

[Dan]

You can indeed, the advantage of using the C/O relays rather than switching relays is that you can use them as normally open or as normally closed simple relays or as a changeover. Just bear in mind the two different maximum current ratings are for the two different outputs. The box with a line is the switching coil, in many cases you are best off using a relay that has a diode or resistor (which is best depends on what you are using it for) across the coil.

[Old Bob]

Many thanks Dan,

Am I right in thinking that I use pins 85 and 86 for the switching circuit and pin 30 with either pin 87 or 87a for the switched circuit?

Bob

[lrostoke]

85 & 86 switching circuit

30 power in

87/87a power out

[Old Bob]

Perfect Thought that icon was ideal for a relay...............

Bob

[dklawson]

Known as both Bosch and ISO relays. Great stuff. I keep a few of the 4-pin and 5-pin relays available in my parts collection. They are always quite useful and are universally available. I must admit though that I buy cheap ones off eBay. So far, no problems, only lots of applications.

EDIT: I forgot to mention, my last application used (2) of these relays in combination with a double-pole-double-throw (on-off-on) toggle switch. The circuit with the (2) relays allowed me to properly power and operate the "round" wiper motor on a budget race car. It was a better solution than cutting up and adapting the original stalk mount wiper switch since the original steering column was gone.

Edited by dklawson, 23 March 2013 - 02:45 PM.