PIC relays control

[Pic_User]

just a little follow up on this

Finally ,I had to order 4.5V relays cuz order 5V we're not stock.
By time things arrived, I spoke with a few people and one told me that some relays were designed to be driven by IC, without anything special requd for protection.

I then decided to give it a chance, and it work! First without a bi-color LED on the pins of the coil, but this would take to much power and only the led would light up.
Removed the led, relay started switching, and kept going

since then I've being debugging/coding for a while, and no problem to report, for the relay.
Coding is another challenge

relays PN is AGN2104H

Hi Dom,

Glad to hear you are making headway. Thank you for the follow-up information. We are all on the learning curve of life.

It is good to get technical advice from knowledgeable people.
Always double check information, at least till you find out which information sources are reliable.

Always read the data sheet.
Always “do your home work” with the technical briefs.

AGN2104H Relay
4.5V nominal 6.75V maximum

If you look at the AGN2104H data sheet:
http://pewa.panasonic.com/pcsd/produ...pdf_cat/gn.pdf

For Cautions for Use, see “Relay Technical Information”.

That brings us to here:
Relay Technical Information (PDF:400KB)
http://pewa.panasonic.com/pcsd/product/re/rti.pdf

Countermeasures for surge voltage of relay control transistor
If the coil current is suddenly interrupted, a sudden high voltage pulse is developed in the coil. If this voltage exceeds the voltage resistance of the transistor, the transistor will be degraded, and this will lead to damage. It is absolutely necessary to connect a diode in the circuit as a means of preventing damage from the counter EMF.

In the Technical Brief, they are assuming you are driving the relay with a discrete transistor. If you are driving from a PIC then the “transistor” is really inside the PIC. The same precautions apply.

Hope this helps,
-Adam-