At a quess, id say that was assumed BEFORE you posted a pic of FIVE terminals on the switch.
Normal 2 connection pushes the led goes off when the push is pushed
Is it safe to run 12v DC LED from 8v AC bell transformer?
- Thread starter haggis999
- Start date
At a quess, id say that was assumed BEFORE you posted a pic of FIVE terminals on the switch.
Normal 2 connection pushes the led goes off when the push is pushed
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Higgis, your drawing is exactly as I had described, but since your transformer is now confirmed as ac, what you can do is modify your wiring a little and connect the wire from the bell not to the top LED + post but to the middle post on the switch first, then take a single silicon diode such as IN4001, or even IN4148 from the center post to +post such that the coloured band on the diode faces nearest to LED +ve post and its other leg to the center post. This will give the LED half wave DC and it should run fairly bright, and yes the LED would go off when button is pressed.
(you can add a small value capacitor such as 22uF - 47uF rated at 25V to smooth the LED Power but I would not recommend this as it would smooth the DC power and average LED current may increase and bring it close to its maximum operating tolerance. Without the smoothing cap LED may shimmer a little which no one would notice easily)
(you can add a small value capacitor such as 22uF - 47uF rated at 25V to smooth the LED Power but I would not recommend this as it would smooth the DC power and average LED current may increase and bring it close to its maximum operating tolerance. Without the smoothing cap LED may shimmer a little which no one would notice easily)
Is your switch a push to activate and not latching? of so then it won't be suitable as a bell button.
I am a bit puzzled by that question. I have never seen a bell button that was not a push to activate and release to deactivate, i.e. non-latching, and have no reason to believe that I have just bought anything different. Surely no one would want any possibility of a bell being left to sound continuously? Have I misunderstood your post?
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Actually, I thought it was impossible to wire the pushbutton with just two wires. The attached diagram shows how I had assumed it needed to be done. This version ensures that the LED stays lit at all times.
Im not totally convinced your FIRST 2 wire drawing works, I will leave others to advise on that.
Just noticed your second 3 wire drawing.
As your proberly aware, Normal bell pushes have just 2 wires, a +VE and a return to the chime, the lamp is therefore in series and lit, using the chime as its -ve return, when pressed the lamp goes off and bell rings.
As far as i know YOUR push would normally use 3 wires, +ve, -ve and a return bell wire, though your 2 wire drawing seems may work.
However none of this answers your query about the voltage, sorry.
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Sorry I have been out, and now I can ease your confusion, I simply asked if your switch is momentary version and not a latching version and all i tried sayiong was if it was a latching version then it won't be good for obvious reason, that you don't want your bell ringing continuously. I started to doubt this because you said that you liked the brushed stainless steel panel with a switch, so you may not have noticed just in case the switch was not a momentary type. Unfortunately I had to assume that you did not know much about switches, but forgive me if you know quite a bit about them, and I am impressed with your drawing skills. Your diagrams look real professional.
And as for light going out, no real issues there as your finger will be covering most of the button and you won't see much of a light through it, and it uses standard twin bell wire or else you will end up using multicore wire to make your bell light on all the time. There is so much choice here and you decide what you want, its your front door, personally I would accept a two wire version for simplicity.
And even if you do choose a 3 wire version, don't forget to wire a diode in series to provide DC half wave rectified voltage, this will ensure that your LED is not subjected to peak reverse voltage as LED tend to not like too much peak reverse volts unlike normal non light emitting diodes, they can stand tons of peak reverse voltage as that is what their role is, i.e. to pass current in one direction and block in reverse direction and you can get diodes blocking a huge amounts of voltages like 700volts for an IN4007, LEDs do not like blocking more than just a few volts, they get destroyed much more easily when subjected to say anything over 12v in reverse. (Each LED manufacturer specifies that reverse limit)
And as for light going out, no real issues there as your finger will be covering most of the button and you won't see much of a light through it, and it uses standard twin bell wire or else you will end up using multicore wire to make your bell light on all the time. There is so much choice here and you decide what you want, its your front door, personally I would accept a two wire version for simplicity.
And even if you do choose a 3 wire version, don't forget to wire a diode in series to provide DC half wave rectified voltage, this will ensure that your LED is not subjected to peak reverse voltage as LED tend to not like too much peak reverse volts unlike normal non light emitting diodes, they can stand tons of peak reverse voltage as that is what their role is, i.e. to pass current in one direction and block in reverse direction and you can get diodes blocking a huge amounts of voltages like 700volts for an IN4007, LEDs do not like blocking more than just a few volts, they get destroyed much more easily when subjected to say anything over 12v in reverse. (Each LED manufacturer specifies that reverse limit)
Only a trickle amount of current flows through the LED, not enough to energise the bell solenoid, when switch is pressed it shorts out LED and its current limiting resistor, then all of the required current flows through the solenoid and hence the bell works. You had your doubts, I have just cleared it.
OK, MikefromLondon, here is my attempt to draw your proposed solution (with optional capacitor shown for completeness). Have I got this right?
BTW, I find AutoCAD LT very useful for this sort of thing. As they say, a picture is worth a thousand words...
BTW, I find AutoCAD LT very useful for this sort of thing. As they say, a picture is worth a thousand words...
Haggis, You have got it right, as for capacitor any value between say 22uF to 100uF rated to 25v, just observe polarity on electrolytic capacitors, they are clearly marked which side is -ve and usually have one leg shorter than the other (again I am assuming you don't know) so the positive side of cap will go to the positive post of the LED and positive of the diode the (Band on the diode side) . So you should be all ok, 2 wire or 3 wire it is entirely your choice.
Very impressed with this auto cad.
Very impressed with this auto cad.
AutoCAD LT is not too bad (about £300/year IIRC), for those who need it, but, as for 'real' AutoCAD, I think you'd probably be very 'impressed' with the (monthly or annual) cost as well as its performance
Kind Regards, John
I just happen to have a 15 year old version of AutoCAD LT that I used to use at work. It still manages to run under Windows 10, with a few quirks, but does all I need for personal purposes. The full fat version of AutoCAD is a 3D program, while AutoCAD LT is 2D only.
I am now going to lie down in a darkened room to ponder all the great advice I have received via this forum over the past 24 hours. The assistance from everyone here is much appreciated
Once I have decided what to do, I will let you know the result.
David
Once I have decided what to do, I will let you know the result.
David
I almost forgot to thank flameport for highlighting cheap Chinese sources of replacement pushbuttons, should that ever be needed. Some of the photos on that link look suspiciously close to my current pushbutton!
It's now looking much less likely that I will be looking for a dedicated 12v DC power supply for the LED, but thanks also for making the point that over engineered solutions can incur a lot of unnecessary cost.
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