Test Box wish list

[JEC]

Wink0192,
Interested, but it depends upon cost.
JEC

______________________________________________

Gary,

Could you explain how Dan's box is checking the quality of the epee tip contact?

Thanks

Jose

[brtech]

It depends on how you plan to display the results of the test.

If it shows three strings of LEDs, with maybe 5 steps of ohms, and 5 steps of 5 ohms, and it's really compact, then yes, I'm interested. I'm not sure a PIC is a better way to do it than a string of voltage comparators, but it may be; it does simplify the power supply. I've looked at this before and the hard part seems to be the analog switch.

What were you thinking of using for measuring? It would be nice if the current through the test was low, so that the whole thing ran on 4 AAs. Usually, ohms law gets you.

While you are at it, I would put in the weapons test circuit like the Favero, with red/green for the active and two yellow intermittent LEDs. I was thinking of using green LEDs for the low ohms, yellow for the intermediate and red for the high ones, so you could just reuse the cord test LEDs. Even more clever would be to use the LED array to show you the actual resistance of the weapon, plus the intermittent flash. Maybe the shorts LEDs could be bicolor, and use red for cord short and yellow flash for intermittent.

If you can do a PCB, I'd like the whole PCB to be maybe 2" x 3" or maybe 2" x 4". You want the display LEDs to be nicely spaced, but you want the board to be only as big as that. Probably put the holes for the 3 pin, 2 pin and mask cord test, and hard wire the bayonet connectors. A 3 position switch for off/cord/weapon test. Maybe a couple of PCB contacts for a lame test setup. If we could find a nice piece of aluminum extrusion for the back and two sides, then we could bend a flat piece for the top and other two sides, and you would have a very small, very rugged, very functional tester.

[Wink0192]

We first start with a constant current source and split it three ways, with diodes. Then send the current, say 5ma down each body cord wire. The voltage at the other end of the cord is a direct result of the resistance in the wire. Feed this voltage into the Analog-to-Digital converter input of the PIC and we get a number that coresponds to the resistance in the wire. Take 10 readings and compute the hi, low, and average value for each line. Then display it on an LCD screen. A good wire will show low for all three numbers. An intermittant wire will show three diferent numbers. A bad wire will show three high reading numbers. Pull and twist the wires to find problems.

Resistance Test - Ohms

Line A Hi = 1, Low = 1, Average = 1
Line B Hi = 200, Low = 20, Average = 131
Line C Hi = 999, Low = 999, Average = 999

This can also be used to test the foil and epee for resistance and opens. A circuit can be added for a foil test where it will light an LED if the point takes longer than 2 ms to bounce closed. Just tap the foil on the table and see if the point opens longer that 2 ms.

There should be infinite resistance between A, B, and C when testing a body cord. The PIC could also test these problems.

If analog type displays are needed, a 10 LED bar graph can be used. One ohm per LED gives a quick visual reference. An LM3914 chip does all the work for the bargraph.

There are a lot of possibilities. What would your dream test box do and how would it display results? My guess is a body cord, weapon, and Lame test unit, in one box.

[brtech]

Originally Posted by Wink0192

We first start with a constant current source and split it three ways, with diodes. Then send the current, say 5ma down each body cord wire. The voltage at the other end of the cord is a direct result of the resistance in the wire. Feed this voltage into the Analog-to-Digital converter input of the PIC and we get a number that coresponds to the resistance in the wire.

Well, that means you need less than .005V resolution in the A/D. What is full scale? 5V? Will that actually work?

Take 10 readings and compute the hi, low, and average value for each line. Then display it on an LCD screen.

Well, maybe, but I think that won't work. I suppose it depends on your sample rate. You implied 10 samples/sec above. Don't want to average 10 samples at 10 per second. If you were running 300 samples/sec, 100 per line, then averaging 10 samples would be 10 displays per line, that would work. If you are using a real LCD display, you probably want it somewhat lower than that, but I think a LED bargraph is a better choice.

A good wire will show low for all three numbers. An intermittant wire will show three diferent numbers. A bad wire will show three high reading numbers. Pull and twist the wires to find problems.

This won't work so well with an LCD display. Just try testing an intermittent wire with a plain digital multimeter and you'll see why it doesn't work. A bargraph works pretty well.

This can also be used to test the foil and epee for resistance and opens. A circuit can be added for a foil test where it will light an LED if the point takes longer than 2 ms to bounce closed. Just tap the foil on the table and see if the point opens longer that 2 ms.

You want what the Favero tester shows you. Red/Green for low ohms, and flash yellow for any change of more than some limit. I'm not sure 2 ms is the right limit, but it's something pretty small.

There should be infinite resistance between A, B, and C when testing a body cord. The PIC could also test these problems.

yes

If analog type displays are needed, a 10 LED bar graph can be used. One ohm per LED gives a quick visual reference. An LM3914 chip does all the work for the bargraph.

No, that won't work. You need around 5 steps of 1 ohm (10 would be better) and 3-5 steps of 5 ohms. You really want to know how bad it is for correct diagnosis. You might want to think about using the PIC to drive a matrix for the displays. If you had 3 rows of 15 leds plus two shorts leds, thats 47 leds, a matrix of 5 x 10 would work well, and may fit in the PIC.

There are a lot of possibilities. What would your dream test box do and how would it display results? My guess is a body cord, weapon, and Lame test unit, in one box.

Yes, as I described, I think you want all three. There is no point in a separate lame test; it's just one leg of the body cord test. Same display, same values, and smaller is better.

I want it very compact (and very rugged).

[rsy]

Originally Posted by fatfencer

My biggest problems is that I cannot read schematics.

Is there anyone out there that has build a test box like these we see in this thread that can do a step by step set of instructions. Mainly for the electrical connections and such.. you know, an Idiot's Guide to building test boxes?

I have no training or experience in any of this, but a year or two ago I followed the advice like that given by brtech, I assembled a small project box, a 6 position 2 pole rotary switch with knob, 10 sockets for the banana plugs, a small analog multimeter with a Rx1 scale, some wire, some solder and a soldering iron.

I made a mess, but I made it work and if I could do it, you can too. Try it.

-r

[Cookeit]

Can someone please post a full list of what I would need to make a test box which can; test body cords (foil), weapons, and lames.
Also, some sort of buzzer should be involved.



And if anyone can show a diagram/schematic that is really easy to follow or can be explained (enough that a high school student could do it) that would be nice.

I have found schematics on test boxes here but I don't really understand them.

[brtech]

You start with Instructions to build a testing box
Instructions to build a testing box

If you can't do that, doing something more complex is probably not the place to start. This is a basic cord/lame tester. It's the type we like to see beginning armorers build and use.

Get that to work. Then come back and we can talk about weapon testing and buzzers.

[Cookeit]

Thanks BR.