Oh dear sorry Bernard, I'm a bit lost. I the transistor the step down thing DJS Fantasi suggested? Or is it the blue thing I used in the oven?
What am I looking at in the picture? Is the bce thing the terminal connector? Sorry you know I'm a bit slow with these schematics

 

Oh dear sorry Bernard, I'm a bit lost. I the transistor the step down thing DJS Fantasi suggested? Or is it the blue thing I used in the oven?
What am I looking at in the picture? Is the bce thing the terminal connector? Sorry you know I'm a bit slow with these schematics

The transistor Bernard refers to is NOT the (converter) module I suggested. My suggestion is only used to change the 24V from the Ledberg power supply to 12V for the accessories that need only 12V.

It’s like having two power sources. 24V and 12V. Each voltage is used for the accessories that need it.

The transistor is a component used just like a switch, to switch on/off your Ledberg lights.

 

The transistor Bernard refers to is NOT the (converter) module I suggested. My suggestion is only used to change the 24V from the Ledberg power supply to 12V for the accessories that need only 12V.

It’s like having two power sources. 24V and 12V. Each voltage is used for the accessories that need it.

The transistor is a component used just like a switch, to switch on/off your Ledberg lights.

I was thinking of doing that, I think I need to put the converter on the lead into the terminal connector not to the microwave. I'll give that a go.

The transistor, well the microwave has a switch that turns it off when the door is open and turns the light on. It's that what you mean?

 

I was thinking of doing that, I think I need to put the converter on the lead into the terminal connector not to the microwave. I'll give that a go.

The transistor, well the microwave has a switch that turns it off when the door is open and turns the light on. It's that what you mean?

The transistor acts like an electronic version of the door switch. It’s so you can use a 12V signal from the control panel to switch the 24V lights on. As you asked in a previous post, quoted below.

Can I ask, if the panel runs off 12V could I still use a 24V light running from a different power supply (arm of the Ledberg) but connected to the same terminal block?

Bernard showed how to wire the transistor as that switch in his post.

 

Oh okay, sorry you know these things are ancient Greek to me, do you mind sending me a link so I know what I'm looking for?

So the BCE in the schematic is my terminal block? Once it's clear in my mind I'll be able to fit it all together like the last time.

 

So the BCE in the schematic is my terminal block? Once it's clear in my mind I'll be able to fit it all together like the last time.

The points labeled BCE are the legs of the transistor. I don’t think they are on the terminal block. Hook it up like you did for the dimming lights in this post.

The leg labeled B connects to the LED output of the control unit. When the control unit turns on the LED, instead it will “switch on” the transistor, sending 24V to the lights on your kitchen.

 

The points labeled BCE are the legs of the transistor. I don’t think they are on the terminal block. Hook it up like you did for the dimming lights in this post.

The leg labeled B connects to the LED output of the control unit. When the control unit turns on the LED, instead it will “switch on” the transistor, sending 24V to the lights on your kitchen.

Ah right, first I get what the transistor is and I'll check where the other one is. (check! *light bulb ding sound*)
So now the schematic is more like mist than mud, okay so @Bernard what am I hooking what up to? That's not clear to me. I have a microwave panel with three wires and the person who created this never said I needed any of this just that I would connect the light so it's all a bit baffling.

So I've read through the schematic which is now more like scotch mist than mud (getting clearer) but what I don't get is where the converter (that runs off B?) connects to and E seems to have two neg connections and I'm not getting that at all.
Could we write the schematic out please like before? B to neg of converter, C to positive etc etc. once I know what goes where, it's easy. When it comes to electronics I'm a "paint by numbers" kinda gal.

 

So Lilli, you received the MW panel with just 3 un colored leads with no instructions on where or how to connect them ? I can see how this might be confusing.

 

Hi @Bernard , thank you. Well I managed to do something new for me and that's upload something onto YouTube! So I have uploaded the video, the guy sent me and I hope that sheds some light (pun!)

In case the video doesn't play or something what I have is a Microwave panel with three leads connected to a terminal connector. I need to connect the following (as per the picture https://forum.allaboutcircuits.com/attachments/20210105_225653-jpg.227012/):

Mains negative | Light negative | Mains positive & Light Positive

When the micowave door is shut the panel will countdown from 10 seconds and then the light comes on when the door is opened, the door has a connecting switch that interrupts countdown when the door is opened.

This is why I am not sure I need a transistor, he seems to have set it up so I can just add a light, the problem I'm having is mainly an issue of overload. When I run the microwave panel off the ledberg, it complains (flashes) to show it's overloaded. When I use the convertor the panel works fine but when I go to add the light once again the panel is flashing. Wondering if I need to put the convertor further up so going INTO the terminal block (part where the red tape is and join convertor to the TC) not coming FROM the block so basically everything is powered down to 12V (not sure if the light will still work though).

Hope that helps make things clearer as to what I have, maybe it will help you to advise, my thanks as always

 

Hi @Bernard , thank you. Well I managed to do something new for me and that's upload something onto YouTube! So I have uploaded the video, the guy sent me and I hope that sheds some light (pun!)

In case the video doesn't play or something what I have is a Microwave panel with three leads connected to a terminal connector. I need to connect the following (as per the picture https://forum.allaboutcircuits.com/attachments/20210105_225653-jpg.227012/):

Mains negative | Light negative | Mains positive & Light Positive

When the micowave door is shut the panel will countdown from 10 seconds and then the light comes on when the door is opened, the door has a connecting switch that interrupts countdown when the door is opened.

This is why I am not sure I need a transistor, he seems to have set it up so I can just add a light, the problem I'm having is mainly an issue of overload. When I run the microwave panel off the ledberg, it complains (flashes) to show it's overloaded. When I use the convertor the panel works fine but when I go to add the light once again the panel is flashing. Wondering if I need to put the convertor further up so going INTO the terminal block (part where the red tape is and join convertor to the TC) not coming FROM the block so basically everything is powered down to 12V (not sure if the light will still work though).

Hope that helps make things clearer as to what I have, maybe it will help you to advise, my thanks as always

I think you need a transistor because the panel runs on 12V and the lights run on 24V. Probably causing the overload.

Let’s find out if I am right.

 

I think you need a transistor because the panel runs on 12V and the lights run on 24V. Probably causing the overload.

Let’s find out if I am right.

Thank you DJS Fantasi! It's all getting clearer with each post. In which case @Bernard if you could talk me through your schematic I think this will get sorted pretty quickly.

 

That is a big help, Lilli, but I have no time today.

 

@Bernard , may I take a shot at an explanation?

Lilli, I have divided Bernard’s diagram into three sections. The transistor switch to turn on the lights is in the left. The lights are in the middle. And the power supply is on the right.



The Power Supply

The power supply (+) connects to the plus side of the light. This could be a position on your terminal strip.

It’s negative connects to a common ground. Thus should be shared with the entire circuit, the light, the transistor (or MOSFET) and the control panel (not shown). This may be a little tricky to understand, but it’s important. It might be another connection on your terminal strip.

The Light

The light positive side connects to the Ledberg power supply as mentioned above.

The light minus side connects to the transistor leg labeled C (for collector). You’ve done this before when wiring the dimming lights for the oven.

The Transistor

Now for the transistor. We’ve talked about the leg labeled C. There are two more connections.

The leg labeled E (for emitter) connects to the common ground from the power supply. That’s it.

The leg labeled B (for base) connects with a resistor to the control panel. It is wired to the control panel terminal for the light control.

Explanation

Then you should be all connected!

When the control panel turns on the light, voltage is applied to the resistor to the transistor. This causes the transistor to connect the minus side of the lights and they will turn on.

Thus will give you a heads up on how this works and how to make the connections in Bernard’s schematic. Hopefully, Bernard will confirm this soon and you should be all set.

 

@Bernard No worries, only when you have a spare moment. Always appreciate when you do.
@djsfantasi thank you SO MUCH for that. We are on our last day of the previous lock down, need to find out what's happening tomorrow, if my son is back at kindy I'll definitely crack on with this or else tomorrow evening. Is that the same resistor as I used before? It was a blue one (sorry I am so layman, I know the blue means something but not quite sure what); oh and thanks I did wonder what BCE meant
PS not seeing where positive and negative of the panel go, seen where the light neg goes. Common ground for power supply means negative from power supply right?

Edit, no just seen where the neg of the panel goes. Think the positive is the bit that connects to the transistor right?

 

Please forgive my confusion in thinking that picture in post # 225 was Ledberg 24V power supply
& not MW panel; just blame it on my 94 years.
There might be 2 options, or more, first the MW panel may already includes the circuit in post # 240 the second would add an inverter to # 240. I'm assuming that MW panel light circuit is open
collector active low. I'll sketch this out in AM.

 

Please forgive my confusion in thinking that picture in post # 225 was Ledberg 24V power supply
& not MW panel; just blame it on my 94 years.
There might be 2 options, or more, first the MW panel may already includes the circuit in post # 240 the second would add an inverter to # 240. I'm assuming that MW panel light circuit is open
collector active low. I'll sketch this out in AM.

No Bernard, I'll blame it on my lack of clarity. Sorry if I wasn't clear enough.
I don't know what "collector active low" means but yes the picture I showed is of the panel. The terminal connector connects three wires, one negative, one for the light negative and then the positive of both the power and light.

I attach a picture of the ledberg, in order to facilitate using the power and light I have cut one of the arms and stripped the wires and done the same with the light, that way I can connect both parts into the terminal strip.

Hope that's clearer. Looking forward to hearing from you. Thanks as always.

 

Here are the rough sketches as promised. Lilli, did you find your remaining transistors ? In option 2 the NPN transistor could be TIP120 if available. I must run.

 

 

Thanks Bernard, going to try with option one, not had a chance to look for anything, lockdown is extended and my oldest is home so is my husband and new baby keeps us busy. Hopefully I'll get a crack at it tonight. :-/

 

Hi Bernard, some success but when I add the light it either doesn't work or overloads.

Checking my connections (option 1)
Ledberg neg to ps12v neg to MW neg
Ledberg pos to ps12v pos to MW pos
Light neg to MW light neg
Light pos to Ledberg pos (a separate Ledberg arm or does it go into the terminal strip with the Ledberg and 12v pos?)

As a back up I've ordered a 12v light, I think this will stop a lot of issues and get things working.

@djsfantasi always happy for your input as you know. Bernard obviously when you have a spare mo, appreciate your time as you know.