|
Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
|
|
|
Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
|
In Reply to: Dumb Relay Question posted by SRMcGee on January 15, 2007 at 06:56:25:
Relays are designed to work at their nominal coil voltages without needing any additional series dropping resistors. The relay you specify has a coil resistance of 69 ohms, so it requires a current of 6 Volts divided by 69 ohms, or approximately 90 mA, to activate the relay mechanism. If your 6V supply is capable of supplying this current, you're good to go wiring the relay coil directly across the supply. Virtually all relays will work OK with coil currents as low as 75% of their specified ratings, so if your supply can't source the entire 90 mA, it may be necessary to insert a series resistance to limit the total current drawn from the relay supply to (6V / Rtotal). To limit the current to 75%, or about 70 mA, would take a resistor of about 21 ohms. The nearest standard value resistor would be 22 ohms. Using this in series would cut the coil current to about 66 mA. If your relay supply would have trouble supplying less than 100 mA, I would have grave doubts about the robustness of the design in general.I'm not clear on the nature of the remote control circuit you propose to use for your project. Does it provide 6V at the relay coil terminal when the remote control is activated (i.e., does it source current) or does it switch the relay coil terminal to ground (sink current) when the remote control is activated? If it sources current, wire the relay coil between the remote control header and ground. If it sinks current, wire the relay coil between a 6V supply and the remote control header connection. It's important to be sure that you have the relay coil voltage polarity right. Although the Digi-Key catalog page I looked at for your Omron relay didn't seem to show one, many relays have an integral anti-spike diode wired across their coils. If you reverse the polarity, the diode will short the coil. If your relay has a clear polarity marking, be sure to observe it. If it doesn't indicate any polarity, then it's probably not protected and it won't matter how you connect the coil.
Hope this helps.
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Re: Dumb Relay Question - RF Guy 05:46:50 01/16/07 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
