Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.components > #6387

Re: IC test clip with LEDs

Cross-posted to 2 groups.

Show all headers | View raw

On 18/10/2018 22:51, Computer Nerd Kev wrote:
> In sci.electronics.components James Harris <james.harris.1@gmail.com> wrote:
>> On 17/10/2018 23:34, Computer Nerd Kev wrote:
>>>
>>> Similar pre-built devices were sold at the same time, but I don't
>>> know of any still available.
>>
>> I wonder why they fell out of favour. Is there a better way to monitor
>> digital ICs in-circuit these days?
> 
> Of course there are Logic Analysers, but they were around back then
> too. These days there are some cheap options for connecting to
> a PC though, eg.
> http://dangerousprototypes.com/docs/Logic_Pirate
> 
> The clip-on indicators were easier to use, but I think the key
> limitation is that the only signals that can be reliably
> analysed are those slow enough for the eye to observe changing
> state. That's why I wanted to build one that allowed various
> methods to be used in order to sample and effectively slow
> down the display.

That's true. As just one example, I have a computer board with a 
4-to-16-line decoder which I suspect of possibly asserting more than one 
output at a time or of not asserting some outputs at all. But without 
single stepping the CPU or running a small test program, which is not 
currently possible, I'm not going to see much from pin states which vary 
so quickly.

I wasn't aware of logic analysers. They sound far better if they have 
enough channels. I see many with 8 or 16 channels but a more expensive 
Hantek LA5034 which apparently has 34 channels: 
https://www.circuitspecialists.com/34-ch-usb-logic-analyzer-la-5034.html. 
Does it look good as a PC-based analyser which could be used in many 
situations, or would you recommend a different one?

Whether such a piece of kit would be generally useful or not, such an 
analyser wouldn't help in this specific case as it could not be used to 
check the above decoder without also using a test program to cycle 
through the inputs. The decoder is not socketed so I guess all I can do 
is unsolder the chip and test the 16 permutations of its inputs on a 
breadboard. If I'm wrong and there is a better approach please say!


-- 
James Harris

Back to sci.electronics.components | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

IC test clip with LEDs James Harris <james.harris.1@gmail.com> - 2018-10-17 21:16 +0100
  Re: IC test clip with LEDs not@telling.you.invalid (Computer Nerd Kev) - 2018-10-17 22:34 +0000
    Re: IC test clip with LEDs James Harris <james.harris.1@gmail.com> - 2018-10-18 17:39 +0100
      Re: IC test clip with LEDs Ralph Mowery <rmowery28146@earthlink.net> - 2018-10-18 12:48 -0400
      Re: IC test clip with LEDs not@telling.you.invalid (Computer Nerd Kev) - 2018-10-18 21:51 +0000
        Re: IC test clip with LEDs James Harris <james.harris.1@gmail.com> - 2018-10-20 11:50 +0100
          Re: IC test clip with LEDs Computer Nerd Kev <not@telling.you.invalid> - 2018-10-21 08:19 +0000
      Re: IC test clip with LEDs Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2018-10-23 12:08 -0400
        Re: IC test clip with LEDs jjhudak4@gmail.com - 2018-10-23 11:40 -0700
          Re: IC test clip with LEDs Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2018-10-25 09:46 -0400
  Re: IC test clip with LEDs "jfeng@my-deja.com" <jfeng@my-deja.com> - 2018-10-17 15:56 -0700
    Re: IC test clip with LEDs James Harris <james.harris.1@gmail.com> - 2018-10-18 17:40 +0100
  Re: IC test clip with LEDs three_jeeps <jjhudak@gmail.com> - 2018-10-18 13:41 -0700

csiph-web