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Woodbob · Jul 17, 2009, 12:56 PM

Hi,

Back to square one! As I reported I decided to sleep on things for awhile and installed the button the way the manufacture requested. Just the diode across the button.

I checked the bell chime and all worked fine overnight. Today it's off, no chime.

Had to switch the circuit breaker on/off to reset.

Now of course I don't know if it was the chime all along! I'm leaving everything as is over night and if it's out again I'll exchange it at Lowe's.

My only thought is was it really defective out of the box or did the LED - Diode - Resistor cause a problem within the chime??

Won't know till tomorrow or perhaps the next day. If I exchange it I'll test it for a full day.

I purchased a resistor substitution box today, thought that might be better then swapping resistors by hand while building a project!

Thanks again

Stratmando · Jul 17, 2009, 01:59 PM

When you say a diode across, do you mean diode or led? I know the led is a diode. With just a diode you will be shunting during the half cycle, loading transformer down.
A diode, led and resistor should work, be sure when all is in place, the LED see the required voltage.

KISS · Jul 17, 2009, 02:23 PM

I did some online searching because the "diode" thing was interesting. What I learned was that without the diode across the button, the chime will supposedly only ring for as long as your holding the button. It is only required on the front doorbel and not the rear.

Based on that information, I do think your only recourse is to use a second 24 VAC circuit and to put the diode across the contacts of the new relay.

Woodbob · Jul 17, 2009, 02:54 PM

Hi,

You are correct about the diode. Hold the button and all works fine. Diode needed.

My question and problem is that even with a relay I'm having difficulty putting the diode across the button when the button is released via a relay. You will always have the led diode and resistor across the button. Adding the new relay the added coil resistance will knock out the chimes if put in series.

You can use the relay to add the diode but when you de-energize the relay there goes the diode. When used the diode is circumventing the Led/Diode - I think??

Can you draw a sketch, please

I could add a separate 24AC Xfrmer and use the button to energize the 24VAC relay and control the 16VAC to the chime through the 24 VAC relay.

My supply and the bell chime are only 16 VAC.. I don't think that's enough to energize the relay.

I still like my Double connector switch.. two SPST (DPST) but I'd need to add some witing to the switch.. Going to dust off my hammer and drill for the walls, just in case.

Thanks

Woodbob · Jul 17, 2009, 02:59 PM

Hi,

Would you know if they make "Time delay" relays that energize w/o delay but de-energize with a set delay..

I know they have time delay relays but I think it energizing??

If there is then perhaps you could delay the circuit when you release the button and keep the chimes going..

Just a thought

Thanks

KISS · Jul 17, 2009, 04:51 PM

I think I have a way to make this a lot simpler.

Pick up a 5V relay 275-240 at radio shack and a small full wave bridge rectifier. The relay has a coil resistance of about 55 ohms.

For now get a 20 mA LED and a 50 ohm resistor, probably 1/2 watt resistor of two 100 ohm 1/4 watts in parallel.

You'll also need a doorbell diode , but let's leave this out for now.

Take the bridge and connect it to the 16 VAC transformer

Connect the doorbell switch (S1) in series with the relay and the output of the bridge rectifier. The DC voltage should be about 7V from the bridge. Don't bother using a capacitor for filtering.

Test. The relay should engage when you push the button. So far, so good.

Now add a diode across the relay coil reverse biased. Plus of diode to (-) of relay. (+) of diode to the negative supply. This is transient suppression.

Now take the 50 ohm resistor and the LED and place across the doorbell button.

Test.

Light should go out when the button is depressed.

You should be able to do this on your bench, if I remember right.

No chime or final connections at this point.

If all works out, you can upgrade the LED and reduce the 50 ohm resistor and test.

Woodbob · Jul 17, 2009, 05:54 PM

Hi,

I'll p/u the parts soon.. Here's a schematic I drew... What do you think?

I realize it has a relay, another transformer and an extra diode.

Will this do it? As you can see the extra diode runs through the NC contacts of the relay putting it across the switch when released.

Thanks

KISS · Jul 17, 2009, 06:01 PM

That's essentially the original design I was contemplating, but I didn't know about the diode across the button thing.

It's correct EXCEPT, the diode has to go across the (C) and (NO) contacts in the correct order.

The 5V DC design looses the transformer.

Woodbob · Jul 17, 2009, 06:15 PM

Hi,

If the diode is moved as you suggest, wouldn't that take it out of the circuit when the button is released, and the chime would stop?

Pushing the button gets it going, and after the relay de-energizes the diode on the NC connects it across the switch. The LED/Diode is only to lite the switch.

Am I missing something.. I toyed with it's placement and did start with the NO side.

Thanks

Woodbob · Jul 17, 2009, 06:17 PM

Hi,

Very strange. The bell is still working

KISS · Jul 17, 2009, 06:31 PM

I think it will work the way you've drawn it, but it's now how the mfr intended. They want the diode across the switch and then the switch shorts it out when pressed. Your circuit doesn't operate that way.

Part II

There is a non-destructive phenomenon with CMOS chips where charge gets moved inside the IC and alters the behavior. Eventually the charge leaks out and the device works again. I had a co-worker who slid a bike with a bike speedometer across the car rug. System broke. Took battery out. Shorted battery terminals. System fixed. I have other stories too.

Woodbob · Jul 17, 2009, 07:04 PM

Hi,

Like I said, I toyed with it's placement. I do know that when I had it across the switch with the LED, and the resistance was too high it didn't work, as if the diode wasn't there.

Actually, while writing this I was looking at the drawing and I believe you are correct.

Putting the diode on between the C and NO puts the diode into the "Front" chime as they designed.

Pushing the button energizes the relay connecting the C to the NO, shorting the diode, releasing again puts the diode back in series with the chime.

I hope!

Hope my bell still works in the AM - just tried it and it's still working.

Thanks

Woodbob · Jul 18, 2009, 05:14 AM

Hi,

Here's what might be the completed schematic w/16Volts. A little down hill drawing but I know electronics can go up hill!

I haven't tried the bell chime yet - too early here.

Thanks

Woodbob · Jul 18, 2009, 09:59 AM

Hi,

I believe I have an error in my bridge set up..

Back soon.

KISS · Jul 18, 2009, 10:10 AM

This is basically what I was thinking of. If I remember my formulas right you'll get about 7 VDC or so. As long as the voltage can cause the relay to pull in you should be fine, otherwise the overvoltage is only going to last for the length of the press.

Woodbob · Jul 18, 2009, 02:24 PM

Hi,

Good news first: The chime works as the mfg suggested - all OK with only the diode in place, no need to exchange.

I bench tested the bridge and got 16VDC out of the Bridge. Is this the over voltage you spoke about? Can't it be reduced to the 7VDC?

I believe I made a wiring error after looking at your sketch.. I put my resistor substitution box together today. I wanted to get something working!

My previous sketch had the bridge wired incorrectly, which I saw before I actually wired it.

I'll give your sketch a try tomorrow.

Thanks for the sketch and help

Woodbob · Jul 18, 2009, 02:26 PM

Hi,

I'll re-measure the voltage after I rewire it correctly.

Thanks

Stratmando · Jul 18, 2009, 03:12 PM

When you say diode, I take you mean Led, is it a 7 volt Led?
The resistor you add should bring the voltage down to LED Voltage.
Since you have 16 Volts DC, To find the resistor, divide the LED current into 16 minus the LED voltage.

Stratmando · Jul 18, 2009, 03:23 PM

I would try the full wave bridge at the door bell, Parallel the ac in on bridge with door bell contacts, then take the DC out, through resistor, then to LED, other lead goes to bridge Minus.
If the full wave bridge is too big to fit in the hole, make a bridge out of 4 diodes, then you can assemble so the hole needs to be big enough for 2 diodes side by side, inline with the other 2 diodes side by side.

Woodbob · Jul 18, 2009, 03:27 PM

Hi,

No, it isn't the LED it's a chime diode. The system is working as it came out of the box.

If you recall I had the normal system stop working after 7 -8 hours that's why I'm testing it as the manfg. Suggested, in case I had a bad chime.

The circuit I'm testing ( Relay - LED - Bridge ) is on the bench.

Thanks again. I'll be at it tomorrow, I think