12v Relay help please

[Nemo1966]

I've been looking at the manuals for the k8055 USB board, and on page 19 of the assembly manual is a diagram of just what you are looking for. ( Mind you, personally speaking, I'd include a diode in parallel with the relay, as in the diagram you have in your post ).

Brill thanks for that.... where did you get the manual? could you send me a link please.

cheers

 

[House0Fwax]

No problem sir,

https://www.electro-tech-online.com/custompdfs/2006/11/illustrated_assembly_manual_k8055_uk_rev3.pdf
https://www.electro-tech-online.com/custompdfs/2006/11/usermanual_k8055_dll_uk.pdf

I have to say that I have built a few Velleman kits and find them to be very good indeed, I've never had a problem, with the exception of one, but that was Maplins fault, as the pack had been opened and the main IC was missing.

 

[Nemo1966]

No problem sir,

https://www.electro-tech-online.com...lustrated_assembly_manual_k8055_uk_rev3-1.pdf
https://www.electro-tech-online.com/custompdfs/2006/11/usermanual_k8055_dll_uk-1.pdf

I have to say that I have built a few Velleman kits and find them to be very good indeed, I've never had a problem, with the exception of one, but that was Maplins fault, as the pack had been opened and the main IC was missing.

Yes I aslo have built a lot of their kits in the past..... but never really had to change anything (all the stuff is numbered) so now having to add something like the switching relay is a bit past my knowledge. Its been really frustrating actually... just trying to find out how to switch on and off an 12v current should be so simple, but a lot of people assume you already have the knowledge needed so skip the details. Yet if i had the knowledge I wouldn't need to ask

and like i say... usually I'd just have a go...... but when its connected to my PC.. I was a bit worried and would rather look stupid asking questions than have a melted PC.

I've pm'ed you

thanks for the links

 

[House0Fwax]

I couldn't read the PM as Firefox (bless 'em) would'nt allow it. Though I have now allowed them for this site.

I think of all the Velleman kits I have made, I have added to all but one. Mind you, I only built their lcd display for something to do.
Also their Pic programmer was just the beginning of much adaptation ( still in progress ). That's why I'm here

 

[Nemo1966]

I couldn't read the PM as Firefox (bless 'em) would'nt allow it. Though I have now allowed them for this site.

I think of all the Velleman kits I have made, I have added to all but one. Mind you, I only built their lcd display for something to do.
Also their Pic programmer was just the beginning of much adaptation ( still in progress ). That's why I'm here

Just got the kit, its very nice. They have examples of the programming interface included on the enclosed CD. The programming of the examples leaves a little to be desired though. e.g I think the programmer did his level best to be as cryptic as possible. I understand it, but I also teach programming and would say that the average person would be quite confused. Not really good as its supposed to show people how to use the DLL in conjuction with the board.

House0Fwax Could you email me on nemo1966 (at) gmail.com please? (Thats all the pm said really..

thanks again

PS have you tried the PicAxe PIC stuff? I have.... quite cool

 

[Nemo1966]

ooooooooooh found a lovely little diagram on the picaxe site:

**broken link removed**

Now that makes more sense to me. what do you think? Ok as is or would you add anything?

 

[Tuxicle]

This would work, as long as the relay coil is rated for 5V operation. 12V relays are more common, but you should be able to find 5V types on Maplin or Farnell. However, the relay turning on and off will inject a little noise into your USB port's +5V line, so I would put a ferrite bead or a small inductor in series with the supply line, so that this won't have a chance of messing something up.

 

[House0Fwax]

Indeed, the diagram makes a lot of sence. It's laid out much better than the Velleman one for sure.
Velleman do have a way of making things seem a bit complicated.
Though on the subject of a 'melted pc', I seriously doubt that you'd have something like that happen. Just to be sure though, when you make the board, try it one step at a time.. I.e.
1. switch an led on and off with it.
2. make the relay circuit and check it independantly with a 5v supply ( nothing connected to it , just see if it clicks )
3. try switching something with it
4. connect to usb controller
5. etc..
6. Woohoo! Celebrate.

Tuxicle has a point about 'noise'. Though as long as you use a smooth regulated supply I don't think it would be an issue, especially as you are dealing with the output from the Velleman unit, and when all said and done, interfacing with relays etc is what it is designed for. If you were buying something from a £1 shop and connecting it to your pc, then, I'd be suspicious. ( melted pc etc.. )

I'll be interested in your progress on this matter, as I said previously, I'm thinking about getting one myself. Not that I need it as such, I just like playing with such things.

 

[Nemo1966]

This would work, as long as the relay coil is rated for 5V operation. 12V relays are more common, but you should be able to find 5V types on Maplin or Farnell. However, the relay turning on and off will inject a little noise into your USB port's +5V line, so I would put a ferrite bead or a small inductor in series with the supply line, so that this won't have a chance of messing something up.

could someone look at this please?

**broken link removed**

Look towards the bottom of the page and there is a 2A DPDT 5Vdc version. Which I assume is 5v switching but also can handle 2A... which is perfect. How can you tell the current draw that the relay coil will draw?

Also:

Which diode would you get for 2A? 1N5400 D027 50 3 <1.1V @ 3A <10µA @ 50V ????

**broken link removed**

thanks

Thanks

 

[Nemo1966]

Indeed, the diagram makes a lot of sence. It's laid out much better than the Velleman one for sure.
Velleman do have a way of making things seem a bit complicated.
Though on the subject of a 'melted pc', I seriously doubt that you'd have something like that happen. Just to be sure though, when you make the board, try it one step at a time.. I.e.
1. switch an led on and off with it.
2. make the relay circuit and check it independantly with a 5v supply ( nothing connected to it , just see if it clicks )
3. try switching something with it
4. connect to usb controller
5. etc..
6. Woohoo! Celebrate.

Tuxicle has a point about 'noise'. Though as long as you use a smooth regulated supply I don't think it would be an issue, especially as you are dealing with the output from the Velleman unit, and when all said and done, interfacing with relays etc is what it is designed for. If you were buying something from a £1 shop and connecting it to your pc, then, I'd be suspicious. ( melted pc etc.. )

I'll be interested in your progress on this matter, as I said previously, I'm thinking about getting one myself. Not that I need it as such, I just like playing with such things.

heres a question:

Which line would you break to control the power to the HD? +12 or -12? or both?

It seems the relay has 2 switches on it.

thanks

 

[House0Fwax]

That relay is not suitable. It can't handle mains voltage. This one would be much better;
**broken link removed**

I realise that it says 6v, but I have just 'clicked' a 12v relay with 4 AA batteries.

On your second point. If the relay is a DPDT ( Double pole double throw ) type, then you can switch both live and neutral. If it's a SPST ( Single pole single throw ) then you can only switch the live. However, that's what most 'mains' switches on appliances do.

On the subject of diode. I'd use an 1N4001. All it's doing is stopping the back EMF ( Elecromotive force ) that occurs when the relay de-energises from possibly damaging the transistor. As an experiment, when you get the relay, try it on 4 AA batteries and look at the sparks you get when you disconnect it.

I'm not sure what you mean by 'Which line would you break to control the switching? +12 or -12? or both?'

 

[Nemo1966]

That relay is not suitable. It can't handle mains voltage. This one would be much better;
**broken link removed**

I realise that it says 6v, but I have just 'clicked' a 12v relay with 4 AA batteries.

On your second point. If the relay is a DPDT ( Double pole double throw ) type, then you can switch both live and neutral. If it's a SPST ( Single pole single throw ) then you can only switch the live. However, that's what most 'mains' switches on appliances do.

On the subject of diode. I'd use an 1N4001. All it's doing is stopping the back EMF ( Elecromotive force ) that occurs when the relay de-energises from possibly damaging the transistor. As an experiment, when you get the relay, try it on 4 AA batteries and look at the sparks you get when you disconnect it.

I'm not sure what you mean by 'Which line would you break to control the switching? +12 or -12? or both?'

Hi, I'm not trying to switch mains voltage. I am trying to build a circuit that will turn on (and off) a 12v 2.0A (max output 24W) device using a 5v control line. (very first post)

I think the conversation through the thread has talked about switching mains at times though.

I was going to switch the mains for the whole unit, but the adapter for the Ext HD outputs 12v so I decided just to switch that. This means I dont have to use a bulky UK 3 pin socket.

Although now you pointed out that relay I may look at doing that again.

So I guess thats where the +12v -12v came in. But you already ansered that with your great "DPDT ( Double pole double throw )" description.

I am struggling to find the transistor needed though ... any ideas?

 

[House0Fwax]

I generally use a BC109C, probably because I have loads kicking around.
Any general NPN type should do, you are only switching a relay. Although you should check that it can handle about 800ma upwards to be on the safe side.
I have jsut tried out the 'Picaxe' circuit on a breadboard using a BC109C and a 12v relay, and a 6v supply. Works fine.
And as for switching the voltage line. Always switch the positive (+) or live depending on if it's ac or dc

 

[Nemo1966]

I generally use a BC109C, probably because I have loads kicking around.
Any general NPN type should do, you are only switching a relay. Although you should check that it can handle about 800ma upwards to be on the safe side.
I have jsut tried out the 'Picaxe' circuit on a breadboard using a BC109C and a 12v relay, and a 6v supply. Works fine.
And as for switching the voltage line. Always switch the positive (+) or live depending on if it's ac or dc

Great thanks!!!

So is the relay I posted OK for the 12v switching?

BC109C is there a maplins equiv?

thanks again

 

[audioguru]

Isn't a BC109 in an old metal case and from about 40 years ago? I still have a few.
Just about any little NPN transistor can turn on a relay in that circuit.

 

[House0Fwax]

Indeed, the 5v relay will be ok. Sorry, I can't help you with the current though, I have never been good with maths and stuff like that. mind you, it's not going to be very much at all.

Any of the following transistors will be fine;
Maplin code
QF28F BFY51
QR23A 2N3053
QB38R BC141-10
VR06G BC639
QB68Y BC337-16
UM82D TIP31C <--- That one is overdoing it a bit, it's a power transistor, but if your branch of Maplin is anthing like mine, then they vary rarely have what you want. So you'd best have alternatives.

 

[Nemo1966]

Isn't a BC109 in an old metal case and from about 40 years ago? I still have a few.
Just about any little NPN transistor can turn on a relay in that circuit.

thank you.

another question, what voltage led will work on that circuit? e.g what does adding the 1.5k resistor do?

 

[Nemo1966]

Indeed, the 5v relay will be ok. Sorry, I can't help you with the current though, I have never been good with maths and stuff like that. mind you, it's not going to be very much at all.

Any of the following transistors will be fine;
Maplin code
QF28F BFY51
QR23A 2N3053
QB38R BC141-10
VR06G BC639
QB68Y BC337-16
UM82D TIP31C <--- That one is overdoing it a bit, it's a power transistor, but if your branch of Maplin is anthing like mine, then they vary rarely have what you want. So you'd best have alternatives.

woooohoooo my shopping list is almost complete ... thanks very much guys for the help. Mucho mucho appreciated.

Now all I need is an LED (see above post)

thanks

 

[House0Fwax]

Uncle $crooge: It is indeed in a metal can. I bought a bag of about 50 many years ago and still use them. I used some about a week ago pic multiplexing project. Old and new components on one board. Teriffic.

 

[House0Fwax]

Any standard led will work, choose your favourite colour. The resistor is there to limit the current.
Some have built in resistors.
Yesterday I bought some nice blue ones from a £1 shop that you mount in your car. ( not that I have one ) However, 3 5mm blue high brightness leds for a £1, yes please.