Circuit testing

[Mikebits]

For many hobby circuit builders, there comes a time when a circuit just does not work. Bewildered as you may be, you search for bad connections, solder blobs etc.

After hours of careful investigation and continuity checks, you wave your hands in despair and surrender. Frustrated at the sight of your blinky board that is not blinking at all.
Of course a oscilloscope would make things much easier, troubleshooting wise. But as you reach into your wallet, only a small amount of currency, and the few coins under the couch you find that the best you can hope for is the oscope ground lead.

Well, it occured to me that the long forgotton logic probe can serve many of your troubleshooting needs, and relieve many of your woes. Knowing whether or not a bit is flipping or flopping is a useful aid in debugging Mr. Blinky.

I Googled logic probe, and found many circuits. One in particular seemed useful as it detects narrow pulses, 50ns I think. I am sure there is a myriad of logic probe circuits out there for the taking, and if you do not own a scope, these little pen sized devices can assist you more than twice their weight.
This one looks pretty good. Don't bother with the piezo buzzer part though.
https://www.electro-tech-online.com/custompdfs/2008/06/k24.pdf

I am sure there are better ones out there, but bottom line is; if you do not own a scope and build digital circuits, you should get a logic probe.

 

[futz]

The "Morgan Logic Probe", available from Peter H. Anderson - Embedded Processor Control is very good. And they're only $2.49 each. Worth every penny!

 

[3v0]

Since the arrival of the PICkit2/Junebug, LA tool I do not use my analog scope near as often.

The Mondo Superprobe is a simple to build DIY probe with 16 functions. The shortest pulse it can detect is 0.5 usec.

Another vote for the Morgan Logic Probe mentioned by Futz.

 

[Mikebits]

That does look nice, very sweet indeed, but you do get my point. Make a logic probe part of your shopping list?

Well shoot, I have written code for 8048's, I suppose I should quit fighting it and jump on the PIC wagon. I have MPLAB 6.02 on my system as I used it long ago. Should I uninstall for Mplab upgrade, or will the new sw do it for me?
Is Mplab still assy lang?

I am only doing this because that probe just looks cool

 

[Mikebits]

Should I uninstall for Mplab upgrade, or will the new sw do it for me?

I meant, will the Mplab upgrade uninstall my 6.02 version, or should I just remove old and reinstall with new verson?

 

[ericgibbs]

I meant, will the Mplab upgrade uninstall my 6.02 version, or should I just remove old and reinstall with new verson?

hi,
microchip recommend that you remove previous versions.

If you have any source code programs I would back them up just in case.

I think the lastest MPLAB IDE is V8.x

 

[rjvh]

before I build something i figured out completly how it works and what i could aspect on various points in the circuit if i perform checks

the only checking device i have at hand now is a multi meter

it hapens a few times that it doesn't work as expected but quite a few times it whas a not working transistor or a diode that whas broken (i use only new components but as it is here a dump ground for all inferiour stuff there is a lot of rejects poping up here)

by studying and knowing what it should do i was always able to repair it

Robert-Jan

mainly the circuits that i build are automation/control circuits

it would be a different situation if it where audio circuits

 

[BeeBop]

before I build something i figured out completly how it works and what i could aspect on various points in the circuit if i perform checks

by studying and knowing what it should do i was always able to repair it

Robert-Jan

mainly the circuits that i build are automation/control circuits

it would be a different situation if it where audio circuits

I think this is how to trouble shoot ANYTHING, including not just audio circuits, and not just electronics....

With circuits, doing the calculations before you begin trouble-shooting tells you what to expect, even if you just estimate the values by doing the math in your head, you will have a rough idea.

 

[rjvh]

I think this is how to trouble shoot ANYTHING, including not just audio circuits, and not just electronics....
.

yes your right it's the same way i aproach problems in a engine or pump/pipe system

The thing that I want to point out is, It would be different by audio circuits if the multi meter is the only instrument you have, you are quite limited what you can measure in those circuits

a scope would be a greater help

Robert-Jan

 

[hugoender]

The "Morgan Logic Probe", available from Peter H. Anderson - Embedded Processor Control is very good. And they're only $2.49 each. Worth every penny!

I just ordered one... it better be good since I took your word for it

 

[futz]

I just ordered one... it better be good since I took your word for it

Just one? Order four! Or six! Make it worth everyone's time.

 

[BeeBop]

Just one? Order four! Or six! Make it worth everyone's time.

I hear if you buy 7, and send 6 off to people you know with in 24 hours, the 7th one will not only last forever, but will make you rich as well.