Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Audible tones continuity tester...

Status
Not open for further replies.
Looks like it was expensive when it was new.
4pyros

The circuit you show (post#15) will not give the tone discrimination the OP wanted for a range of 0.1 to 5 Ω. A 5 Ω change in the top resistor is only a 0.1% change in discharge time and roughly only one tenth of that in the charge time. The OP wanted the frequency to more than double over that range.

John
Yep, just an example of how it could be done.
 
Looks like it was expensive when it was new.

Yep, just an example of how it could be done.

No, I don't believe that circuit can be made to do what has been asked. Play with the component values that would be needed, and you will find out for yourself.

John
 
No, I don't believe that circuit can be made to do what has been asked. Play with the component values that would be needed, and you will find out for yourself.

John
Yes I under stand, but its not up to me, its up to the OP.
 
the one i have is a mili ohm meter designed to trace shorts apparently, i used one at school and they are really good, the one with the all in one probe like in your picture is really ace
 
From the service manual it seems that big probe works by detecting the magnetic field resulting from injecting current into the circuit under test. So it's a current-trace probe. The two smaller probes are for the Ohms test.
 
From the service manual it seems that big probe works by detecting the magnetic field resulting from injecting current into the circuit under test. So it's a current-trace probe. The two smaller probes are for the Ohms test.
is that for the 580? i have the 550 and i thought that was just ohms? and for detecting shorts? i must get it out again and have a look tomorrow
 
Seems like most of there modles have inject and trace for testing and repairing circuit boards.
 
mine isnt made anymore and i think it was the base model, they wernt chap and even now they can still cost a fair bit second hand unless you get lucky like i did ;)
 
is that for the 580?
Yes. The manual gives schematics for both models, but the Current-trace Module is only in the 580.

The Ohms unit works by passing a known current (switch-selectable according to Ohms range) through the resistance-under-test, DC-amplifying the resultant voltage across the resistance, then displaying the amp output and using it to vary the (audio) frequency of a square-wave generator. The square wave is used (indirectly) to drive a speaker. The audio frequency increases as the resistance decreases (contrary to what the OP wants).
 
Last edited:
thanks i didnt think mine had the trace, its got the probe but thats because it was owned by a numpty
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top