Doorchime Voltages: AC/DC And I Don't Mean The Band... "Einstein" Input Welcome :)P - Electrical - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum Doorchime voltages: AC/DC and I don't mean the band... "Einstein" input welcome :)P

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05-28-2010, 05:18 PM   #1
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## Doorchime voltages: AC/DC and I don't mean the band... "Einstein" input welcome :)P

Hey everyone,

So, I've hit on another roadblock... Now I'm certain (99.9%) that there's a simple calculation/answer -- but I don't know what it is!

I've got a door chime. It's got a motor that rings a little bell (literally 'a bell that moves back and forth ringing') -- on the motor it reads 6 Volt DC power or it's got the option to take 4, or 6 - can't remember, "C" batteries.

Anyway -- there's no companies out there that offer a 6 Volt DC door-chime transformer that I can find...

The most 'variable' transformer from HD offers outputs of 8VAC-10VA, 16VAC-10VA or 24VAC-20VA

My assumption is that 6 volts DC may be equivalent to something in an AC voltage "OR" that I'm just hitting a roadblock on finding a 6 volt DC door bell transformer.

Does anyone have any insight on if there's an "equivalency rating" for 6 volts DC, for door-chimes, or if there is a 6 Volt door-chime transformer out there...

The strange thing is that I remember looking online ages ago and I could swear that I found one place that offered a 6 VDC transformer for door-chimes out there (and it wasn't in Europe -- I've already seen they sell them)...

Anyway -- thoughts, comments, suggestions --- ANYTHING!

Thanks all

 05-28-2010, 07:55 PM #2 Sparkaholic   Join Date: May 2010 Location: Miami, Florida Posts: 192 Rewards Points: 150 If 10 VA @ 6 V will run your motor an Edwards #596 transformer will give you that, but that is AC! You'll need a little inline or diode rectifier to get the DC voltage you need to run your DC motor! Here's an inline I found on a quick google search: http://www.qualitydoor.com/Adams-Rit...er-p-1063.html __________________ Answers based on the mood I am in when you ask!

 05-28-2010, 08:33 PM #3 Member   Join Date: Jul 2008 Location: NW of D.C. Posts: 5,990 Rewards Points: 2,000 You need to know how much current your chime uses. A C cell is usually used for a 100 mA supply but doorbells are used intermittently so the drain might be higher. These put out unfiltered DC http://www.hosfelt.com/contents/en-us/d6.html so your bell might sound strange using them. You could say a battery puts out perfectly filtered DC. A 'battery eliminator' comes close to putting out DC as smooth as a battery and might work better. Radio Shack, and others sell them. Last edited by Yoyizit; 05-28-2010 at 08:45 PM.

 05-29-2010, 08:09 AM #4 Newbie   Join Date: May 2010 Posts: 19 Rewards Points: 10 Thanks for the help guys -- sparks1 -- I looked up that Edwards t/f you mentioned -- I can only find it has a 12v output...? But I like your idea after that to convert to DC... If I could really find the 6v variety, then you're on to a winner... (http://www.residential-landscape-lig...LLD3219EDW.htm) Also, Yoyi, thanks for your suggestion too... I looked, but would like to try and stick with transformers that are dedicated for the task of door-chimes if possible... In other news, I had a look in more detail and the motor is manufactured by a company in NC called http://www.buehlermotor.com/ -- the model number seems to be not listed on their website but I've now e-mailed them too as a means to seeing if they have any idea too... I still have my heart set in the belief that a higher AC voltage, coming from a regular door-chime transformer, may be sufficient to run this thing without causing damage - the power only causes the motor to twist in one direction maybe 40-80 degrees (just a little bit) - the drive is attached to a coiled 'spring like' piece of metal attached to a bell. The 'spring' amplifies the movement from the motor's little twist and rings the bell... I did some more research and came up with this... http://www.electro-tech-online.com/g...rt-vac-dc.html Now I know it's not specifically what we're talking about - but is there a general consensus/thought/opinion that a slightly higher VAC voltage would be enough to power this thing without causing harm? Thanks again for your help everyone
 05-29-2010, 08:18 AM #5 Master Electrician   Join Date: Mar 2010 Location: Indiana Posts: 4,413 Rewards Points: 5,082 IMO an AC only xformer will not work especially at a higher voltage. As others have said a rectified AC voltage or a direct DC source should work. A rectified 6 volts AC will produce a slightly higher than 6 volts DC.
05-29-2010, 10:16 AM   #6
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Quote:
 Originally Posted by Dazzlin I did some more research and came up with this... http://www.electro-tech-online.com/g...rt-vac-dc.html Now I know it's not specifically what we're talking about - but is there a general consensus/thought/opinion that a slightly higher VAC voltage would be enough to power this thing without causing harm? Thanks again for your help everyone
That's a pretty good forum for designing circuits at the component level, and Gibbs, Goodwin and Boncuk have been there for a while.

More voltage = more power = more of a temp. rise above ambient. For every 10C increase in operating temperature the design lifetime halves, but coils are inherently reliable.
For this intermittent duty application you could probably go to 9vdc and the thing still wouldn't fail.

05-29-2010, 10:21 AM   #7
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Quote:
 Originally Posted by Yoyizit That's a pretty good forum for designing circuits at the component level, and Gibbs, Goodwin and Boncuk have been there for a while. More voltage = more power = more of a temp. rise above ambient. For every 10C increase in operating temperature the design lifetime halves, but coils are inherently reliable. For this intermittent duty application you could probably go to 9vdc and the thing still wouldn't fail.
OP says it runs a motor so the increased voltage is going to speed up the motor. It probably wouldn't hurt the thing but it will not sound the same.

05-29-2010, 10:30 AM   #8
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Quote:
 Originally Posted by nap OP says it runs a motor so the increased voltage is going to speed up the motor. It probably wouldn't hurt the thing but it will not sound the same.
That's kinda' why I'm wondering how smooth the DC needs to be to make it sound the same.

Unfiltered full-wave-rectified AC will have 120 Hz riding on the DC output. Filtering this will reduce the peak-to-peak amplitude of the ripple voltage.

It also may be that no one notices the difference unless they are specifically listening for it.

05-29-2010, 11:48 AM   #9
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Quote:
 Originally Posted by Yoyizit That's kinda' why I'm wondering how smooth the DC needs to be to make it sound the same. Unfiltered full-wave-rectified AC will have 120 Hz riding on the DC output. Filtering this will reduce the peak-to-peak amplitude of the ripple voltage. It also may be that no one notices the difference unless they are specifically listening for it.
it's not a matter of the DC being smooth. DC motors speed are affected by voltage so more voltage equals more speed. I imaging the little dinger would be zipping pretty good at 150% voltage.

as to using filtered or unfiltered DC. There is where I doubt you would notice much difference. It is a bell which in itself is "sounding" intermittently when it is operating properly. The little clapper hits the bell, retreats, hits the bell, retreats...

I doubt you would notice a choppy DC causing any problems

Now, if you were using the same motor and power system, listening to a record (that's something we used have long before many of you kids were alive) might cause a noticeable sound problem.

Last edited by nap; 05-29-2010 at 11:52 AM.

 05-29-2010, 04:11 PM #10 Newbie   Join Date: May 2010 Posts: 19 Rewards Points: 10 Hey guys, Thanks for all of the replies -- Unless I'm missing the point -- am I understanding that possibly an 8v AC door-chime transformer would be OK without causing any long-term damage to the device? I've attached an image of the unit, so you all get an idea of how the motor works -- as you can see the motor just rocks a few degrees in one direction and back again causing the 'spring' to amplify and make the bell ring -- hopefully the consensus will be that this shouldn't have too much in the "cause & effect" of performance -- all I'm most interested in doing is avoiding any long term damage to the motor. Thanks again all -- you've all been really helpful... All comments welcome... Attached Images
05-29-2010, 07:53 PM   #11
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Quote:
 Originally Posted by Dazzlin I've attached an image of the unit,
The spring and bell has a resonant frequency that does not change, so for proper operation the motor speed should remain constant. There may be electronics inside to ensure this constant speed while the battery voltage drops.

Do not put AC into this thing.

Knowing the current draw, a simple filter circuit will give you an acceptable peak-to-peak ripple
http://en.wikipedia.org/wiki/File:Smoothed_ripple.svg
If it runs on 4vdc to 6vdc I guess it can tolerate 2v P-P ripple.

For 'zero' ripple and a constant 6.0vdc use an LM317 regulator
http://www.national.com/mpf/LM/LM317.html#Overview
and put smoothed DC into this regulator circuit with a minimum value of 8vdc.
Depending on the current draw you may need to put a heatsink on the regulator, but I doubt it.

Last edited by Yoyizit; 05-29-2010 at 08:04 PM.

 05-29-2010, 08:01 PM #12 Member   Join Date: Sep 2007 Location: NY lower Hudson Valley Posts: 233 Rewards Points: 196 Google"6vdc power supply " and you will find what you need for \$10 bucks
 05-29-2010, 09:19 PM #13 Sparkaholic   Join Date: May 2010 Location: Miami, Florida Posts: 192 Rewards Points: 150 You know, it seems rather odd that this doorbell motor is set up to run on batteries and can also be run by an outside source that requires DC voltage. If this is so I would bet if you check the schematics it either has a rectifier built in or they sell the power supply for it as an accessory. It doesn't make any sense for a company to make a residential doorbell that has an option for external power that doesn't accept AC voltage unless they also sell the power supply! __________________ Answers based on the mood I am in when you ask!

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