relay wiring

[HiGain]

Could someone PLEASE explain how to wire a DPDT relay. I've done some searches, but don't seem to have the brain power to figure it out. I also checked to the file section.

Is there a schematic around that tells an electronic dummy like me precisely how to wire one of these things?

Second question. Can I activate the relay with a non-momentary switch, like a standard stomp switch?

Thank you.

Jake

[heisthl]

The relay is just an electronic switch, in your case a DPDT. Check the pinout for your particular relay - many are like this when viewed from the bottom - leftmost contacts are coil, then next 2 are common, then normally closed and lastly normally open. Apply the correct voltage to one of the coil terminals and by grounding the other coil terminal you will hear it click. The click tells you the common terminal has just changed its connection from the normally closed to the normally open terminal. In most amp applications you will keep the relay power supply ground isolated from the rest of the amp and wire your footsitch to connect this "special" ground to the relay coil. Most builders put a diode across the coil terminals to reduce popping noise being injected into the audio. Connect the cathode(stripe) of the diode to the same coil terminal you are using for the supply voltage and the anode to the terminal you are using for the ground. This is assuming you are using a positive relay supply voltage.

[Normster]

Relays baffle the hell out of me when I first look at them on a schematic. I take a very methodical approach by first drawing the relay and marking C, NC, and NO (common, normally close, and normally open). From there I plot one connection at a time starting with the common, then NC, and lastly, NO. I know it sounds too simplistic, but I'm a simple man.

[Bob-I]

Second question. Can I activate the relay with a non-momentary switch, like a standard stomp switch?

Thank you.

Jake

There are many types of relays, but 2 that apply to us.

The common ones are non-latching. They switch when power is applied, and stay in that position until power is removed. For these you need an on-off footswitch like used on Fender amps. This is what I use, and most folks here.

The other type is a latching relay. When power is applied they switch. When it's removed they stay. Apply power again they switch again. This is the type you'd use with a momentary switch.

So make sure to buy a non-latching relay and you'll be fine.

[Luthierwnc]

It is easier to conceptualize if you think of the switch and the coil separately. They run on completely different circuits. On the schematics available, these switches are usually drawn as SPDT with a connecting line on the poles to make the traces straighter. I always redraw mine just like they look on the back of the relay or the layout diagram. It is a mental trick but it has led to some "ah-hah!" moments.

One thing to watch, a lot of relays have the pole in the center of the switch lugs. Others put it on the end nearest the coil. Be absolutely sure which is the normally-open throw, the normally-closed throw (on with no power) and the pole.

Skip

[HiGain]

Wow.... I actually do understand

So, the relay Gary uses,

http://www.mouser.com/search/ProductDet ... MI-SH-212D

http://relays.tycoelectronics.com/datasheets/OMI-2P.pdf

THis is a NON latching, correct? I did not see where on the datat sheet this was specified.

Second question. Can you cantrol two or more relays with a single switch without any circuit alterations?

Thanks so much!!

Jake

[Tdale]

yes, if you want several relays to activate at the same time, using one switch, you just keep adding relays, and wire the coil circuits to the same stomp switch. The limit is probably when you have so many relays that the coils draw more current than your power supply can handle.

Tommy

[HiGain]

Thank you for the answer.

About the method mentioned above to reduce clicking with a diode. Does the threshold of the diode matter? In other words, germanium, schottky, 1n94 type, power diode (1n4001), led, etc.

Thanks, everyone.

Jake