relay coil that heats.
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Solid State Talk all about solid state amplification.

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
 24th April 2013, 01:12 PM #1 Project16   diyAudio Member     Join Date: Nov 2012 Location: Cognac relay coil that heats. Hi everyone! I just finished a DC protection for speaker and everything works as expected. But I have a question for the relay coil heater. My question is simple: It is normal that the heater coil? Thank you!
 24th April 2013, 01:41 PM #2 jaycee   diyAudio Member   Join Date: Apr 2004 Location: Norwich, UK No, the coil should not get hot. If it is, then there is too much current flowing through it. Are you using a higher voltage than the coil is rated for ?
Project16
diyAudio Member

Join Date: Nov 2012
Location: Cognac
Here is the diagram, the original and the change I made was with the 12v relay.

Regards!
Attached Images
 dcdetectschematic.png (46.5 KB, 138 views) dcdetectschematic-mod.png (46.1 KB, 133 views)

 24th April 2013, 02:46 PM #4 jaycee   diyAudio Member   Join Date: Apr 2004 Location: Norwich, UK The zener will not do what you think. The diode is there to catch the EMF kickback the relay coil produces when it is de-energised. You have 24V across a 12V relay, which is why the coil is overheating. The easiest solution here is to add a resistor in series with the relay. Measure the resistance of your relay's coil, then add a resistor that will drop the required power using the Voltage Divider formula. For example, if your relay's coil is 400 ohms, you would do R = ((24 * 400)/12) -400.
 24th April 2013, 02:50 PM #5 Project16   diyAudio Member     Join Date: Nov 2012 Location: Cognac jaycee thank you, I will modify and test! Regards!
godfrey
diyAudio Member

Join Date: Nov 2009
Location: Cape Town
Quote:
 Originally Posted by jaycee The easiest solution here is to add a resistor in series with the relay.
Even easier, since he's already got the 12V Zener - just put the Zener in series with the relay coil. That will drop the 24V down to 12V.

 24th April 2013, 03:22 PM #7 AndrewT   R.I.P.   Join Date: Jul 2004 Location: Scottish Borders Godfrey, that makes the relay pull in very susceptible to variation in mains supply voltage. __________________ regards Andrew T.
Rundmaus
diyAudio Member

Join Date: Aug 2005
Quote:
 Originally Posted by AndrewT Godfrey, that makes the relay pull in very susceptible to variation in mains supply voltage.
In principle yes, but I don't think this will be a problem, as most relays pull in at approx. 85% and, once activated, remain in the on position down to even lower voltages.

I would worry more about the Zener diode passing approx. 100mA while dropping 12V, making for 1.2W dissipation. Not every small Zener diode will take that in free air.

Rundmaus

 24th April 2013, 06:18 PM #9 jaycee   diyAudio Member   Join Date: Apr 2004 Location: Norwich, UK I did consider putting the zener in line but a resistor is far better for the job, and a 1W resistor should be adequate
Rundmaus
diyAudio Member

Join Date: Aug 2005
Quote:
 Originally Posted by jaycee a 1W resistor should be adequate
Doubt that.

At least, the nominal relay coil current should be looked up and the actual dissipation in the series resistor should be calculated. If my rough estimate of 1.2W is right, I would at least use a 2W or even 3W resistor to avoid excessive surface temperatures.

Rundmaus

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         Dx Classic Amplifiers         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post VMat Parts 7 18th November 2012 09:24 PM Coconuts 500 Parts 5 1st September 2012 05:38 AM kavermei Tubes / Valves 5 11th April 2010 01:53 PM cal34 Parts 0 15th February 2009 08:33 PM ThSpeakerDude88 Car Audio 9 23rd January 2007 03:24 PM

 New To Site? Need Help?

All times are GMT. The time now is 11:46 PM.