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New interrupter with display(fully logic)

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LAN_403

Reaching

Fri Jun 01 2007, 11:14PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

Yes the title says everything. I wanted to build a interrupter which can display the on and off time in real time on 7 segment displays. it was really complicated to build it all with easily available logic ics but heres is what i came up with..

The on time is adjustable between 0, yes 0 ÂµS and 360ÂµS . The off Time between 5,2 and 18mS. the count decade consists of 3 4026 7 segment counters.
a 1mhz signal is generated by the crystal oscillator. in the on time period a 7400 switches the 1mhz signal to the counter decade. a rc with 1k/1nf is used to get the reset signal. the count and display time are also made with nands. to count the off time a 1/100 divider is used to get a 10khz signal. the squarewave generated from the first ne555 is divided by 2. so i can count the on time in ÂµS and the off time in mS ans 10th of mS

here are a few pics and a video

And if someone wants to rebuild the interrupter, heres the shematic.

it was a good and cool project to test my logic skills ;)

...

Sat Jun 02 2007, 02:39AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Ah, there will always be a place in my heart for circuits made with all logic chips.

I am also impressed that you managed to get the chips packed that tight on a single layer board with so few jumpers

Reaching

Sat Jun 02 2007, 08:40AM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

... wrote ...

I am also impressed that you managed to get the chips packed that tight on a single layer board with so few jumpers

Thanks, And the back doesnt look like a forest of wires too. I had a few bugs in the board so i had to solder a cap and a resistor on the back.

There are still to many jumpers on the board. yesterday i had to look on the board layout to get the bugs solved, i managed that i wired some jumpers up which are nonsense. but who cares of 2 more jumpers. it works and thats what counts.
It doesnt look like, but the circuit is in fact really simple. im still on the search for a ic that can handle 3 or more 7 segment displays

The next thing is to put it in a nice case. i also have to build the "burst" controller. a oscillator is tuned at the secondary resonant frequency and counts the bursts within the on time period. so you know in realtime how many hf bursts you send through the coil. thats just useless i know, but i like displays :)

Part Scavenger

Sun Jun 03 2007, 01:09AM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

Mighty nice Reaching!

Sparrow338

Sun Jun 03 2007, 06:01PM

Registered Member #661 Joined: Sat Apr 21 2007, 03:17AM
Location: Ventura, CA
Posts: 41

Very nice! Very clean and thought out setup.

I don't really know much about these 7 segment driver ics but will this work? It drives up to eight 7 segment displays.

http://www.elabinc.com/ede707.pdf

Wolfram

Sun Jun 03 2007, 09:17PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

Making that chip work in this project would require a lot of work and probably end up at more ICs than in the original design.

JimG

Mon Jun 04 2007, 01:54AM

Registered Member #52 Joined: Thu Feb 09 2006, 04:22AM
Location: Austin TX
Posts: 57

That's really cool. I bought a bunch of CD40110s a few years ago in the hopes of building a similar interrupter, but wound up going with the LCD display and microcontroller route.

After seeing this I may try to revive that project.

Steve Conner

Mon Jun 04 2007, 09:49AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Looks great, just watch out for EMI! For instance what if spikes got into your interrupter circuit, triggered a bunch of flip-flops and made the duty cycle jump to 100% :-0 A malfunction like this could blow your DRSSTC to kingdom come. I'm not saying your circuit is bad, just suggesting you mount it in a shielded case with appropriate filtering and isolation, and be watchful for trouble.

edit: I looked at the schematic and it seems to be an ordinary analog interrupter with a digital readout, so I guess my concern isn't really valid.

Reaching

Mon Jun 04 2007, 07:33PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

Thanks @ all. I wanted to show with this project, that there is no need for a ÂµC to realise a display function for an interrupter. and yes, its an ordinary dual 555 interrupter.

And of course, iÂ´ll put the interrupter in a nice metal case to shield it from emi.. okay, maybe the displays will run mad in drsstc duty or so, but the interrupter itself wont. i havent tested the circuit on a drsstc yet so i dont know how much the emi will affect the logic, but i hope that they wont care much

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