Quasar Four Digit Up/Down Counter: Triggering Relays & Using with Magnitude Comparator

I recently acquired one of these - a four digit up/down counter from Quasar, the company that advertises each month at the front of  Everyday Practical Electronics magazine
No doubt the counter will be very old hat and old technology to many of you. But it kept this hobbyist amateur amused for several hours putting it together from a kit. And to my delight, once assembled it worked first time. You can't ask better than that.
What the company didn't include with the kit that I thought it might usefully have done to increase its educational value and general interest for the hobbyist were some hints, tips and examples of clever things that might be done with it.
For example, I'd like to have it trigger a relay when the count reaches a certain point. Can that be done, anyone know?
I also thought of buying a duplicate kit from Quasar and to use the two to feed two separate sums into a magnitude comparator. Is there a way of doing that?
Michelle O'Brien,SE London

Hi Michelle-That looks like a nice counter. I'm glad you're thinking about ways to hack it to add features.The chip that is doing all the work its an Atmel MCU.  Adding the features you mention will require modifying the firmware in that chip.  If you can get your hands on the code (and maybe the schematic too), it will make it a lot easier. If you can't get access to the code, at least the chip is in a socket, so once you find out what the schematic looks like it wouldn't be that terribly hard to develop code from the ground up.  I couldn't read the numbers on the chip in the picture,   but I'll bet if you do a search you'll find some 4-digit counter code examples for that chip.  If you do, it may still require some minor changes to the code to get it to run on your hardware.-Rick

I failed to address your last question- rather than have two counters and a magnitude comparator it would be a more solid (although more complicated) approach to build new hardware with as single MCU with enough pins and horsepower to serve as two 4-digit counters + comparator.  
-Rick

Hello Michelle.  I found the Quasar site and they do make some tasty stuff.  And it's always nice when things work first time - well done!  The one you got does not have a circuit diagram unfortunately, but it does say"The circuit used in this kit uses only one IC – the
AT90S1200..."Now to my mind there are two routes you can take here.  You can learn programming and mess around with the AT90S1200 program and make it do what you want (or maybe start from scratch and base a new design on that one) or you can go back to basics and get yourself a breadboard and a couple of 7490's or 74390's (these days you'd get the 74LS or 74HC versions) and a 555 and play around with them.  They are counter chips that count to 10 - one counter in the 7490 and two in the 74390.  They give BCD (Binary coded decimal) outputs on 4 lines and could then certainly be able to feed into a 7486 comparator. Or a 7447 decoder to drive a 7-segment displayThe thing about doing this is that you're working at the coal face, so to speak, dealing direct with the logic of a counter.   You could start off just feeding the counter outputs to LEDs and then work towards getting them to do some triggering on a certain count.  You'd have fun with this and learn a lot more as well, though programming is a good skill to have as well...If this would be of interest I can point you towards some more resources that would help you.

If you are looking at the 74HC90 and 74HC390, look also at the 74HC162 and 74HC163, to see fully-synchronous counters. These are more than you need for simple counters, but can provide inspiration for more advanced projects.

Although the 74C925, 926, 927, and 928 are obsolete, they are still available and make very nice single-chip 4-digit counters.
-Rick

AT90S1200-12PC

Michelle I was thinking about this a bit.  Let's say you wanted to make an Egg Timer.Your counter can count down and it will give an "overflow" output when it reaches zero.
First of all you'll need minutes and seconds, values of 60, not 100.  Your module can't do that.Secondly you'll need an accurate clock for your timer, so you'll have to set up a 555 timer, or a crystal oscillator, or derive it from the mains, or something, to give you one pulse a second.You'd probably also want to make some circuitry to stop the count when it reaches Zero, and something to stop the alarm when you've taken your eggs out....Now you probably think I'm going to say "Hardware counters are better than microcontrollers!" but not at all.  It just reinforces my point that you either need to get to the point where you can program you own microcontroller applications (and I'm not sure how easy it will be with this kit - do they give you a software listing and programming instructions? OR you make your own task-specific hardware using digital logic chips.  This kit - while it is very nicely made and could be used in a number of projects - is pretty limited unless you can get at the software that drives it.. .. If you go the hardware route you get something that is also difficult to change or repurpose without some knowledge.Your idea of comparing two counters.  You could do that with this kit by comparing the 7-segment display outputs, but you'd need 4 7-bit comparators (you can get 8-bit ones).  With a hardware solution using BCD outputs you'd compare those instead, and you'd only have 16 bits to compare instead of 28.  More manageable.  But then, with something like this, you'd do it in software, but you need to be able to program.....It strikes me that someone should devise a "universal" kit that has:- decimal or minutes/seconds counts selectable- "preset count reached" alarm with optional stop- "zero count reached" alarm with optional stop- inbuilt optional one per second clock pulses (and maybe other values)- on board sounder and maybe a couple of buttonsMaybe that someone should be me..... or you ??

"Let's say you wanted to make an Egg Timer."Egg timer? No way, David. Thanks for contributing but I've a kitchen clock with a sweep second hand for egg timing. No, I want something that registers the number of steps  ("up"/"down", depending which way - clockwise/counter-clockwise) the shaft of my stepper motor is turning. For these purposes can we assume the shaft  is going round at a good old 200 steps per revolution - no clever half-step/quarter-step stuff here for the moment, please.
So the four digit up/down counter module I've bought  will register  up to 1,999,800 steps (200 x 9999), which works out at a total of 49.995 revolutions of the stepper motor's shaft - plenty enough for my purposes.The idea is to be able to stop and start the stepper (and maybe even to get it to go backwards/forwards) at preordained points in the count.
The counter works perfectly. But having seen it in action I realize now that it's a simple soul and I can't envisage how I can make it do what I want without some drastic messing-about with - and additions to - the circuitry. Which to be honest is beyond my technical competence.Any bright ideas would be welcome, as long as they're not toooooooo complicated. Otherwise I guess my only options are to buy a more sophisticated counter module fitted with presets and relays or look for a solution involving the Arduino.Arduino? Now, there's an idea.Michelle

Michelle sorry, I wasn't trying to talk down to you there, it's sometimes difficult to know where to aim without going over someone's head, especially in these columns.  I reckon I hit you somewhere just above your knees.... :-)But you're right, and my points still stand....your counter is a simple soul and nowhere near capable of doing what you want beyond just indicating the position of a stepper. And you'd have to divide the stepper pulses by 200 before you even got to the counter module - more logic ICs.If you're au fait with the Arduino I reckon that would be a good solution to your problems.  That's eminently capable of driving a stepper motor, counting the pulses / position, driving an LCD display for a menu and / or interface for setting parameters, and (to save pins) driving your counter to display the position nice and big and bright (three pins - one for clock and one for down/up, and one for reset).  The Arduino could do the dividing internally and pulse the counter such that it displayed between o and 49.99 as appropriate.  You'd have to put the decimal point in but that's probably a strap on your counter board (if not I'm sure that would be easy to hack).Let us know how you go....

Hi Michelle,It does seem to be a simple counter and David is right Arduino is a  way to go to get what you want.But you can use the Cypress PSoC 5 development board (sub £12).I have already built a breadboard project for  a useful half and full step stepper motor driver with Up /Down count, forward and reverse all done in programmable hardware and the output displayed on a 4row  * 20 character LCD display. I thought I would add a synchro resolver to check  that the output via a belt does not slip against the steps programmed.I live in Hampshire (UK near Portsmouth) and would be happy to work with you to get the result you want.Just so you can fully understand my madness look at my last article on EEweb Crusty Bits: Using Stripboard for Electronic Projects There are other articles as well.Best Crusty aka (Conrad Mannering)

Thank you, everyone, for all your kind and useful advice. So without heading down the Arduino route just yet and keen to explore ALL avenues, can anyone tell me,  please, would investing in one of these be worthwhile for the sort of thing I'm  seeking:

https://quasarelectronics.co.uk/Item/smart-kit-1172-up-down-counter-dual-relay-output

Hi again Michelle.  There are a lot of things to consider here. One of them is count rate, some of these counters only count at 25Hz or so which may be too slow if you are using a stepper motor,I had a fossick (Australian for "look around") on Quasar's site and though there are some pretty good kits there are none for which I could not see problems with what you want to do.  Many of them have presets which I think you need, and most have at least one relay output that will activate when a preset count is reached.  but they all seem to have things that would get in the way of what you want to do.The disadvantage I can see with the kit you linked to is that it does not seem to have accessible contacts for inputs you can provide.. Now I am sure a lady of your abilities can solder wires to the switches to let you use the inputs externally, but nowhere does it give a specification for counts per second.  Since it is designed for use with a push button switch it may only be able to accept a couple of inputs per second which would probably render it useless for what you want.Quasar offer two Cebek kits that may do what you want, here's one
https://quasarelectronics.co.uk/Item/cebek-cd-5-4-digit-up-down-counter-preset-relay-module
they also offer a 6-digit version.  BUT it seems that once the preset count (or zero) is reached, it stops and you have to activate a "Next" contact to make it do anything else, you can't just carry on by counting down.  Weird. They seem to be from Spain as the English in the instructions is not how the Queen would talk, and some of it's still in Spanish....The Velleman 8035 kithttps://quasarelectronics.co.uk/Item/velleman-k8035-multifunctional-up-down-counter-kit
is a strong contender, very versatile, gives doesn't seem to stop and need resetting, just gives an output when the programmed count is reached.  It can count up to 200/second which should be enough for what you need? (oh, and it does time as well, so you can use it for an egg timer   This kit is pretty reasonably priced (16 quid) and Velleman have been around a long time and I have a great respect for their products.I may not have picked up on all your requirements and I suggest you look at these kits (particularly the manuals or specifications) and think about whether they will do what you want.  Let us know if you have any queries in that regard and we can try to answer them.Cheers/ David

 

Michelle...that is one of the Cebek ones I referred to above, with the weird NEXT input that you have to use to restart it when a programmed limit is reached:"To unblock the circuit and to continue to count up / down without erasing the displayed number, you
have to activate the Next input. At the opposite, to unblock the counter up/down, coming back to the
start number, you have to activate Reset input."If you just want to count up and down with it, you can't use the programmed limits without using that Next contact it seems, so you'd then have no indication that your limit is reached.  You may be able to work around this depending what you are driving it with.  More in the manual here.Also, all of those models are out of stock (see at bottom of the first link above.)