The side of the LED with a "nipple" on the side is definitely GND (-). The blue in my diagram is the Live (+) side.
When I connect GND to the DC- and the LED+ to the DC+ the relay powers up.
It is not obvious how the LED GND is connected back to the Boards GND...I can't follow it on the board
When testing VCC and GND against the LED terminals I get varying degrees. Board LED Reading
VCC - 0.86V
VCC + 0V
GND - 2.07V
GND + 4.38V
Do you think that because there is a constant 0.92V running through the LED that that is enough to switch/trigger the relay as soon as its connected and the fact that it increases to 2.4V is irrelevant because it is already registered as "High" just because there is a current?
May a resistor between the LED+ and Relay IN possibly reduce that constant current so that only when it is increased it registered?
MAS3:
And LED 3 is connected to the same VCC through 2 via's.
But it looks like those 4 LEDs are all tied together, because the cathodes seem to be all connected trough smaller via's too.
Is that correct, do all 4 LEDs light at the same time ?
The yellow wires (to a buzzer or speaker ?) and the sticker obscure my view so i can't see all i'd like to see from your pictures.
You are talking about current, but show values measured in Volts.
Voltages seem to be correct, but please try to use the correct term.
LED 2 and 4 have actual LED's "that flash" connected to them and LED 1 and 3 seem to be dummy's. Current flows through them in the same way as the other two but there is no actual light connected. Seems like they have been put there so I can solder my relay cables to them. Very thoughtfull I thought.
Yes the yellow wires connect to the buzzer. I have removed the sticker and attached photo.
You are correct I appologise, very sloppy of me I will be more acurate, I am measuring voltage only at this stage and not amps/current.
If that is the case, you can set the jumper so the relay triggers on LOW. You have to do this because the LEDs appear to be switched on the LOW side. The red and black wires you have shown appear to be correct.
I believe that the essential part of the circuit is this, based on some of the markings on the board and what has been said. The component values are approximate.
If that is correct, the ideal point to connect the relay trigger is not on the LED but at the point where the LED is switched. The problem is only finding this point. The components Q1 and R7 on the board appear to be candidates any may be you can test the voltages there when the LEDs are flashing.
Yes there are.
How else did you think i could make remarks about wires and a sticker obscuring my view of the board.
I can see only 1 component which is marked as a transistor; Q1.
There's also a component marked U2 with a similar SOT3 housing, but U2 suggests it's an IC instead of a transistor.
That one is connected to VCC through a resistor, and is close to a SOT 16 chip which markings lead me to thinking it is a RF receiver (but this housing isn't documented as far as i could see).
Q1 is connected to an IC (U6) which could be a 555 to create the flashing pattern, together with U1 but for both of these components it's impossible to see any markings (but hey don't seem to be the same type of chip).
Because of it's designation U1, that may be a controller like an ATtiny (but that would make the use of a 555 not very logical).
But now i'm guessing a lot here.
So i'll leave it at this and go to bed, as in 7 hours or so the 1st working day of this year is on.
I think it is very difficult to find out what is what (hard enough for me if i'd be holding the pcb in my own hands, but remotely i doubt i'll manage. But how about we just amplify the signal, where there should be an LED, we put an opto-coupler an PC817 the current provided should be enough to open it up and drive the relay with vcc from the pcb. Not the most technical solution but pragmatic. Personally i would have started building something from scratch, but now we are on this track if we can get there using 1 or 2 more components i think that would be the best.
Deva_Rishi:
No, you don't have it wired up correctly a BC548 is an NPN, You should wire it up as such and power it from a different source (with common GND) what kind of relay is it ? 5v ? 12v ?
I posted a reply to this but it doesn't appear to have "taken", so here's another try. Apologies if I end up duplicate-posting.
Is an 1N4148 up to the job of serving as a "flyback diode" for a relay? From the specs, it looks like that's a low power switching diode, and only has very modest current-handling abilities. It looks to me like 1N4007 would be a better choice. (Disclaimer: I'm a software guy, and not an expert on electronics.)
Deva_Rishi:
No, you don't have it wired up correctly a BC548 is an NPN, You should wire it up as such and power it from a different source (with common GND) what kind of relay is it ? 5v ? 12v ?
Paul__B:
The specs of the diode must exceed those of the coil - that is, the current must be rated greater than the coil current (because at the moment of switch-off all of that coil current will be flowing through the diode, though not for too long) and the rated voltage greater than your supply voltage (because that is the voltage which will appear across the diode when the coil is energised).
So a 1N914/ 1N4148 - a signal diode - is generally the wrong choice except perhaps for a relay operating well under 100 mA. Generally, a power diode with ratings as above will be more appropriate. On the other hand, if (but only if) you are going to use PWM, then a fast recovery or Schottky diode will be needed.
Yeah, looking at specs it looks to me like 1N4007 would be a better choice. (Disclaimer: I'm a software guy, and not an expert on electronics.)
Ignore my duplicate post. I am still getting used to this forum and was on the wrong page of replies.
DuncanC:
I posted a reply to this but it doesn't appear to have "taken", so here's another try.
Paul responded earlier as well, then changed his mind, the people at Velleman use these, i figure they're ok for most of the relays i use, but i am not fussed if you want to use a heftier one.
DuncanC:
Is an 1N4148 up to the job of serving as a "flyback diode" for a relay? From the specs, it looks like that's a low power switching diode, and only has very modest current-handling abilities. It looks to me like 1N4007 would be a better choice. (Disclaimer: I'm a software guy, and not an expert on electronics.)
Yes, I would have thought so also having habitually considered these as "signal diodes" but the datasheet of the relay he has
gives a coil resistance of 70 Ohms, which at a working 4.9 V would give a current of 70 mA, which is well within (by a factor of two to four times) the limits of those diodes whose datasheets I linked in your quote.
It turns out it is way more than adequate for the job.
Going back to post #20. This part I missed and looking at the board, I can't see that it is correct (assuming all the LED positions are connected in the same way.
The side of the LED with a "nipple" on the side is definitely GND (-)
From this picture, it appears that LEDs 1, 2 and 4 ( I can't see 3) have a direct connection to Vcc
That means that the other side of the LED (with the "nipple") must be switched to GND to light it. If LED 3 is connected in the same way, it would imply that the connection you have made with the blue wire to the LED3 pad is effectively to Vcc. That would then be the wrond side of the LED to trigger the relay.
Do you have a multimeter where you can test the resistance between corresponing LED pads to see if these are all
connected in parallel [DISCONNECT FROM MAINS WHEN YOU DO THIS TEST]
Your table in the post is not clear maybe because of the formatting, did you mean this, where the the point where you took the measurement on the LED was where you have shown the blue wire on the "non-nipple" side of LED3 ?
Board LED Reading
----- --- -------
VCC Off 0.86V
VCC On 0V
GND Off 2.07V
GND On 4.38V
6v6gt:
If that is the case, you can set the jumper so the relay triggers on LOW. You have to do this because the LEDs appear to be switched on the LOW side. The red and black wires you have shown appear to be correct.
I believe that the essential part of the circuit is this, based on some of the markings on the board and what has been said. The component values are approximate.
If that is correct, the ideal point to connect the relay trigger is not on the LED but at the point where the LED is switched. The problem is only finding this point. The components Q1 and R7 on the board appear to be candidates any may be you can test the voltages there when the LEDs are flashing.
Attached is the picture of the board and relay spaghetti junction I am working on..... I have switched the relay to LOW but then it does not power on at all. Also I am connected to the LED1 just incase that makes a difference, I assumed they are all the same
I think you're onto something with Q1! :o
One of the points is 0V when on stand by and 3.5v when LED's are flashing, let me solder an extension on that piece (marked in red on pic attached) and try connect the relay again.
6v6gt:
Going back to post #20. This part I missed and looking at the board, I can't see that it is correct (assuming all the LED positions are connected in the same way.
From this picture, it appears that LEDs 1, 2 and 4 ( I can't see 3) have a direct connection to Vcc
That means that the other side of the LED (with the "nipple") must be switched to GND to light it. If LED 3 is connected in the same way, it would imply that the connection you have made with the blue wire to the LED3 pad is effectively to Vcc. That would then be the wrond side of the LED to trigger the relay.
Do you have a multimeter where you can test the resistance between corresponing LED pads to see if these are all
connected in parallel [DISCONNECT FROM MAINS WHEN YOU DO THIS TEST]
Your table in the post is not clear maybe because of the formatting, did you mean this, where the the point where you took the measurement on the LED was where you have shown the blue wire on the "non-nipple" side of LED3 ?
I connected the "blue" wire to the non-nipple side which I assume is the VCC side, is IN on the relay not supposed to be connnected to the VCC side of the LED?
I'm not really sure how to measure if they are all in parallel....?
Regarding the table:
The LED - and + referred to the GND and VCC side of the LED's
"-" = GND (nipple side)
"+" = VSS (non-nipple side
anyway, let me solder that bit to Q1 and I'll let you guys know how what happens
Just be very careful in the area of LED1. It is (physically) very close to rectified mains voltage. An earth leakage circuit breaker, strong rubber gloves and thick rubber mat would be useful precautions to take in this area !!
A zero to 3.5 volts swing (relative to GND) when the LEDs are flashing should be an ideal point to operate the relay module. This point is probably the base of the transistor which switches the LEDs. If, after connecting the relay, the LEDs no longer flash, maybe put a 1K resistor in series with the relay trigger wire.
Ive now connected the Q1 to the relay as per the attached photo.
On std by the relay is on and the "triggered" red light on the relay is on with the power light, when the LED's flash both the power light and the "trigger" light on the relay flash too but the relay does not "switch"
I'm getting mixed readings when connected or disconnected to the relay
Connected:
VCC - Q1 = 2.3V (std by) and 3.9V (led flash) although the readings do range between 2.9V and 3.9V while the LED's are flashing
GND - Q1 = 2.1V (std by) and varying between (0.5V and 1.5V) when flasing
Disconnected from relay:
VCC - Q1 = 0V (std by) and 4.3V when flashing
GND - Q1 = 4.37V (std by) and varying between 1.5v and 3.5v when flashing
I'm very confused?
Also on a different topic all together I always have the same soldering problem.....
Touching the solder on the iron melts it like butter immediately but as soon as I introduce the board into the equation nothing.... I hold the tip on the board/solder expecting it to melt but nothing happens.
I will have to hold it there for seconds, sometimes up to a minute or more until it briefly melts so quick that I don't have time to react and then go rock hard again and nothing.
Test the tip and solder away from the board and it melts like butter. I have this problem everytime I try to solder, it messes up the board because sometimes I hold it there for so long the board startst o go black and melt.
I have a HAKKO F888D set I don't think the fault lies with the heat or the iron, it may be the point tip but it's probably me. I've got a chisel tip on order so maybe that will help
I don't really want to disctract from the doorbell problem in hand but if someone knows what I'm doing wrong then that would help...
Just be very careful in the area of LED1. It is (physically) very close to rectified mains voltage. An earth leakage circuit breaker, strong rubber gloves and thick rubber mat would be useful precautions to take in this area !!
A zero to 3.5 volts swing (relative to GND) when the LEDs are flashing should be an ideal point to operate the relay module. This point is probably the base of the transistor which switches the LEDs. If, after connecting the relay, the LEDs no longer flash, maybe put a 1K resistor in series with the relay trigger wire.
In hindsight choosing LED1 was not the wisest, I will connect to LED3 (opposite side) next time. That is exactly what happened to the second doorbell alert device, I blew it when taking readings becasue I touched one of the 230v terminals.
I'll try the resistor, my solder was too shit so has come loose and I'm really struggling with this one because the Q1 contact is so fricking tiny ( I struggle with soldering at the best of times! argh!!!)
Ignore post 34. I connect the rely with the VCC to the IN and the Q1 to VCC blah blah stupid idiot not concentrating......
I still don't quite believe it but it is working! Heheeee!
So connection is as per the photo in my previous post.
VCC to DC+
GND to DC-
Q1 to IN
Relay switches on/off as the relays flash..... Amazing! I can't believe this has been such a struggle.
The sound no longer seems to work unfortunately but I have to order another one anyway as I may have damaged the board somewhere with all my amateur welding, cleaning the tip helped!
Thank you Deva_Rishi, MAS3, and a special thank you to 6v6gt!
As always the great folk on this forum have come to the rescue
Once I've got it all safely wirded and boxed up I'll post a pic....
Touching the solder on the iron melts it like butter immediately but as soon as I introduce the board into the equation nothing.... I hold the tip on the board/solder expecting it to melt but nothing happens.
The solder used in those PCB's is not quite the same type as what you have (it is meant for robots !), but i tend to get the best result by warming up the point to solder and then add a tiny bit of solder, the surface for heat transfer increases a lot like that and the 2 solder types mix. after doing this the solder on the pcb tends to melt easier. (definitely melts with the wire if that has been tinned properly as well)
and power it from a different source (with common GND) what kind of relay is it ? 5v ? 12v ?
