Discussion in 'PCB Layout, Design and Manufacture' started by grantos, Sep 5, 2013.

1. ### grantos

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Sep 5, 2013
hello everyone,

what i have is a motion sensor, with a pcb inside. Basically the pcb has a mono jack attached, so when the sensor is triggered, instead of making a noise, a signal is sent along the phono cable, to a panel on the wall, that alerts the nurses in a care home. i have attached photos of the pcb, is it possible to copy this onto a breadboard? or will i need to get pcbs made up? also does anyone know what the components are on the pcb?

if anyone knows how to make this circuit on a bread board, or draw a diagram so i can make one then please get in touch!

i would really appreciate the help with this as i am quite a beginner with circuits!

thanks.

2. ### Harald KappModeratorModerator

11,794
2,749
Nov 17, 2011
For starters:

draw each component with its pins onto a sheet of paper. Draw all connections between the components as they are laid out on the PCB. This first draft will most probably look very entangled.

Next, rearrange the components and connections such that a neat diagram results.

From that circuit diagram, place the components on a breadboard an connect them with wire stubs according to the diagram.

Here is a tutorial that shows how to work with breadboards.

3. ### grantos

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Sep 5, 2013

i have drawn out the circuit on illustrator and colour coded the tracks,

do you have any idea what the two small black components are? one has '2B1' on it and the other '124'.

I'm guessing the orange component is a resistor, does the colour indicate the size/type?

thanks

4. ### Harald KappModeratorModerator

11,794
2,749
Nov 17, 2011
The 2B1 could be a zener diode or a transistor. If it's the 2-pin device, its the zener diode, if its the 3-pin device its the transistor. I can't read the codes from the image.

124 is probably a resistor 1.2*10^4 Ohm = 12kOhm. A multimeter would come in handy to verify this.

5. ### grantos

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Sep 5, 2013
ok thanks, its the 2 pin device so looks like its a zener diode!

heres a bigger photo, still not sure what the other 2 are

6. ### Solidus

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Jun 19, 2011
The 2B1 is a SOT-23 transistor, the markings on the other are consistent with standard diode markings. If you can layout the circuit more fully we can have a better idea of what it is. By that I mean, show us what's on the other end of the motion detector.

I'm working on deducing a schematic of this device, but what logically should be a ground in most cases is now breaking out to a red wire. It'll take me a little bit to get adjusted to this circuit.

Harald, does that appear to be a relay? It looks to me like a potted DPST relay.

Last edited: Sep 6, 2013
7. ### grantos

4
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Sep 5, 2013
yeah i have a multimeter, what should i put it across on what setting?

the sensor is a nurse call sensor used in care homes, when someone crosses the beam at night, instead of sounding the alarm, i'm guessing a signal is sent out of the motion sensor, along the wire, where the 1/4 inch jack is plugged into the wall, then the signal goes from there to the main nurse station. Hope this explains it enough!

thanks.