Add on electrical circuit board

[PeterR]

With diode, means there is a diode in the relay. What is does is keep the current from backfeeding through the relay, they are good for isolating circuits with multiple power supplies, or for use on a charging circuit.

Also, some relays have a protective diode parallel to the coil.

When the circuit feeding a coil is opened, a large voltage is generated across the coil (like the primary of an ignition coil) and it is fed back to the components connected to the coil.

If the coil is fed from a simple mechanical switch this is unlikely to have much effect, but if controlled by a solid state device the spike can cause permanent damage.

To prevent this, relays intended for these applications have a diode parallel to the coil.   The diode faces upwards, which a descriptive way of saying under normal circumstances it does not conduct, and so far as the rest of the circuit is concerned the diode does not exist.     When the feed circuit opens and the spike starts to build up, the diode becomes forward biased and effectively provides a short across the coil proving a path for the energy to dissipate and protects the circuit components connected to the coil.

When these relays are used it is important to have the polarity of the coil terminals correct or the diode will burn out the first time the coil is energised.

[Crosley.In.AZ]

I am off on another tangent here;


I am of the opinion we need this information for wire harness, relays , etc  on the tech page .

We also need a section with web links for certain lines of parts.  I know we have a general  links section.

Web links for the small parts we all need in this hobby.  The recent companies mentioned by enjenjo for wire terminals, relays and related bits.

Perhpas a section where we can locate a RRT member that is a small dealer for certain lines of parts?  I am not sure how many companies will provide drop shipments from the factory for these dealers.

I am just rambling on here.