Continuity Tester Project

prprog · Apr 14, 2015

MCU88 said:
I am talking about an actual 'real world' electronics shop. Not eBay and websites. Things are different in the 'real world' My profit margins would be textbook thick.

I will be so great to have such a shop were I live.
Where is you shop located?

Thanks,
PRPROG

Externet · Apr 14, 2015

The very best ever continuity tester I have found and use since maaaany years :
----> https://s588.photobucket.com/user/Innernet/media/P1010196_zpscbfb7439.jpg.html?sort=6&o=35

MCU88 · Apr 14, 2015

Cicero said:
I know this is minor, but for the unused opamp, I like to pull the inputs to different potentials, just to ensure no ringing and you know the output state.

Thanks for point this out. And I agree it might oscillate. I have just fired up TraxMaker and made the amendments to the PCB. Be nice to get the board a bit smaller so that it can fit in the tiniest of project enclosures. Project like this belongs in an box for all practical usage. The prototype works well on my bench, so I am going to run with the design despite what you may or may not think of it. It works. It is cheap. Simple as that.

MCU88 · Apr 14, 2015

prprog said:
I will be so great to have such a shop were I live.
Where is you shop located?

The shop is located near a prison in Australia. Long bay jail. This is an max security prison for ***********.

Give it a rest with your un-necessary references to various sexual stereotypes - MODERATION

Colin · Apr 15, 2015

This is a continuity tester as well as a LED tester:

MCU88 · Apr 18, 2015

Colin said:
This is a continuity tester as well as a LED tester:

View attachment 92022
View attachment 92023

Nice board. Too rich for me though.... I have to make mine from scratch. No silkscreen printing. No solder masking. Single-sided only.
Here's one that I did a while back:

Works out to be about $2 plus labour. Gets even cheaper if I can step a few of them up on one large board and guillotine them into pieces.

NorthGuy · Apr 18, 2015

How are you going to produce this?

MCU88 · Apr 18, 2015

NorthGuy said:
How are you going to produce this?

Completely in-house. Manual labour. Laser printers. Thermal transfer paper. Blank copper clads. Chemicals. Guillotines. Zip-lock bags... for parts...

AUD 14.95 in real life retail shop (batteries not included)

NorthGuy · Apr 19, 2015

If you use a PCB manufacturer, you will go below the cost of raw materials at quantity of 100 or less. You will get an added benefit of solder mask and silk screen (although some manufacturers will do bare boards too). It will happen at much lower quantities if you consider reducing PCB size by using more compact double-sided design.

MCU88 · Apr 19, 2015

NorthGuy said:
If you use a PCB manufacturer, you will go below the cost of raw materials at quantity of 100 or less. You will get an added benefit of solder mask and silk screen (although some manufacturers will do bare boards too). It will happen at much lower quantities if you consider reducing PCB size by using more compact double-sided design.

Hell no... I'll do the whole thing myself. Keeps me busy and out of trouble. Plus I do not support the notion of cheap overseas labour where people are working with dangerous chemicals such as ammonium persulphate all day every day for 2-dollars an hour. We are taking advantage of slave labour to fuel an hobby here...

shokjok · Apr 21, 2015

JimB said:
My first thoughts are about sledge hammers and nuts...

A more positive thought is:
Why not make a meter to measure low resistance, say less than 5 or 10 Ohms, and have an adjustable alarm point setting so that as you are "buzzing out" a cable or whatever, the thing will sound to tell that there is continuity if the resistance is less than some value set by the user, say 2 Ohms.

JimB

If you work in the auto service industry, you'll learn about decade boxes that are used to simulate and troubleshoot sensors and dash gauges. These decade boxes have resistances down to 0.025 ohms, allowing for wire resistance.

MCU88 · Apr 27, 2015

JimB said:
My first thoughts are about sledge hammers and nuts...

A more positive thought is:
Why not make a meter to measure low resistance, say less than 5 or 10 Ohms, and have an adjustable alarm point setting so that as you are "buzzing out" a cable or whatever, the thing will sound to tell that there is continuity if the resistance is less than some value set by the user, say 2 Ohms.

JimB

Jim this project presented here does exactly just that. The threshold / adjustable alarm point is set by turning the trimpot. It can be set from anywhere between a few milli ohm to a couple of hundred ohms.

MCU88 · Apr 28, 2015

I now have this boxed up... and it works a treat! ...

Nigel Goodwin · Apr 28, 2015

MCU88 said:
I now have this boxed up... and it works a treat! ...

Looks really nice, well done.

MCU88 · Apr 28, 2015

Nigel Goodwin said:
Looks really nice, well done.

Thanks

I am toying with the artwork though. Any suggestions?

flat5 · Apr 28, 2015

All you may need is a 9v battery, resistor, piezo sounder with built in oscillator, two wires with probe endings.
I once made one for an assembly line that tested cable harnesses and they were happy with it.

MCU88 · Apr 28, 2015

flat5 said:
All you may need is a 9v battery, resistor, piezo sounder with built in oscillator, two wires with probe endings.
I once made one for an assembly line that tested cable harnesses and they were happy with it.

Yeah of course you do whatever you can get away with if it is just a job to you. You are there to satisfy the customer and get paid. No more no less. If the customer pays for the job it means they are 'happy'

Most of us here are geeks though. It is not just a job and a pay cheque. Genuine passion for the desire to create works of originality. Making money from it is a cherry on top of the self-satisfaction and merit.

flat5 · Apr 29, 2015

I was a test technician. They were assemblers that could not always have access to an ohm meter.
I built it for fun for them. Put it in a cardboard box. I forgot to say the resistor went across an electrolytic capacitor to discharge it.
The sounder made a kind of sigh if the continuity was good. The gals liked the thing. Made them smile.

My point was it can be complicated or very simple. Could be a battery and bulb.
I did not mean to criticize your work.

Nigel Goodwin · Apr 30, 2015

I think we need to put this into perspective

'Value added features' - he's hoping to sell this device as a kit, and you're not going to make any money selling a battery and light bulb in a cardboard box. The added features of this design, plus the fairly impressive appearance, means it's got some sales potential - the fact that it's actually much higher performance is probably only of minor importance to the target audience?.

NorthGuy · Apr 30, 2015

The box looks really nice. Why not to use colors in the artwork?

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