Ravi

Hi Friends,

I am trying to build a LED Osciloscope. The display is a LED matrix. This is being controlled by LM3914 and two CD4017. Anyone knows where can I get some ideas?

Mosfet

This was a Forrest Mims article in Popular Electronics August 1979.
It used the LM3914, one 4017 and one 4011.
The resolution left much to be desired.
You could try a google search on his name and oscilloscope.
Or try and find a copy of his Engineer's Notebook.

hotwaterwizard

Here it is.

Attached Images

LED Oscope.gif (63.5 KB, 47 views)

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Ubergeek63

That jerk was such a quack. His mantra was quantity, not quality. Only about a tenth of his crap was unique, and that was not even his!

Back in the day three quarters of the Radio Shack books were his crap. 30-100 "projects" each all based on the same two or three circuits.

You are better off with one of the free PC scope programs that use the sound card's mic input.

Torben

Today it would seem foolish. In 1979 it would have been magic to the hobbyist (or at least quite useful).

It would still be a fun project.


Torben

Ubergeek63

i suppose so... I remember I had antique tube scope and saw it when it was published

picbits

I used to sell the books "back in those days"

Anything that got the kids interested in Electronics that didn't cost the earth was a worthwhile book.

I started off with a book by R A Penfold - still got it in the attic.

Ubergeek63

I guess I was different. I recognized and despised the tactics even when I was ten. better to pay $10 for a 10 in one kit than $3 for 30 versions of the same pathetic circuit.

microtexan

I found the Forrest Mims books very useful and educational. They had plenty of circuit ideas and useful circuits. I still refer to them from time to time to kick start a project. Sorry you didn't enjoy them for what they were.

Admittedly, he made money from them as well as did Radio Shack, but I believe the books helped a lot of people get into electronics. It's just a shame there are so few parts stores like Radio Shack used to be, thank goodness for the mail order houses on the web.

HarveyH42

I think the idea was to show all you could do with a handful of common and cheap parts. Electronics wasn't a cheap hobby back in the 70's. As a kid, I had to make do with what I could salvage. I was thrilled to find any circuits to build with parts I could get for free. Wasn't a huge Radio Shack fan back then, and still won't go to one as an adult. The parts were of the cheapest quality ( remember, I'm comparing to what I salvaged), and the prices were just way beyond what I could afford. So, as a basic introduction to electronics, with little or no money, I'd guess those books served a purpose other then just profits.

picbits

I went to my first ever Radio Shack store in California a couple of months ago. I'd worked for Tandy in the UK for many years and it was like stepping back in time.

Quite a lot of the same old junk (with the same old catalogue numbers) that I used to sell many many (20 !!!) years ago.

Did feel good stepping back in time though - my Tandy days were good fun and it was a sad say when they were bought out in the UK and closed down

Nigel Goodwin

'Bought out'?, I thought they just went bust, and a mobile phone company took over the sites?.

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picbits

I've heard various different explainations as to why they were bought out and also why they were closed down so I won't comment too much on that.

I know back in my day they were quite often getting into financial problems with rumours of baliffs waiting for the store managers to open up and not letting them in to the store until debts were paid at head office.

That said there were always a lot of rumours going around at that company lol.

Ubergeek63

Guess I was just past them before they were out. Even in middle school I was referring to data sheets and appnotes