1-in-4 sequencer freezes up--a noise problem?

Hi, Bruce. I'm not familiar with the circuit. Could you describe it a little better, or at least indicate which ICs are used? Or, if you're feeling energetic, post a sketch or go to

to download AACircuit and you can post the circuit here.

Cheers Chris

It's very likely noise on the power rails. Do the SSRs have snubbers? Do you have at least a .1 uF bypass cap at each chip and a 10 uF or so for the whole board? Are you running the 120VAC through the board that the chips are on? Then take a look at your power routing - there could be inductive or capacitative coupling to your power leads or even to your signal lines.

And, as Chris said, please show us a schematic of what you have now.

Good Luck! Rich

Thanks for the note, Rich. I LOVE this Google groups--so many helpful people come out of nowhere to help a lost soul who's strayed way out of his depth! I've downloaded AACircuit, and realize I'll have to bring the schematic home and learn a bit how to use AAC before I can hope to post it. Luckily, a 3-week break is starting Saturday, so I should have time to learn a WHOLE NEW THING (That's what I love about electronics--it goes on forever that way.) I see the CD 4011 14-pin DIP is not one of the choices in AACircuit, so I assume I'll need to draw the internal gates that it contains. I THINK I'm up to the challenge. I hope to send a reply to you soon.

As for your suggestions, I know what "SSR" means, but I confess ignorance: what's a "snubber"? Also I assume the .1uF bypass cap just go across the + & - inputs for the CD4011. Thanks for your advice. I'll keep you updated if I make any progress, and try to get a schematic posted here soon, too.

Bruce

Rich Grise wrote:

A snubber is just a little circuit, usually a resistor and capacitor in series, that momentarily absorbs switching transients. They're really important if you're using inductive loads.

Here's the first hit when googling for "snubber network" - there's lots more:

And, the convention here is to bottom-post. This is USENET. The google groups site is only a gateway. Usnet isn't a chatroom, it's not a website, and it's not email. :-)

For best results, you should find out from your ISP what the URL of your news server is, and use a proper newsreader.

Good Luck! Rich

Its not by accident that Google is causing the confusion.

Tom

Dear Rich,

Well, I followed your advice (which I think I will also try on a TV Gameshow-type lockout buzzer (Who's answering first?) unit I built and had continual problems with. It has been sitting in a box for years, but maybe, just maybe sprinkling some .1uF caps. . .), and put .1uF caps across the CD 4013 and 4001 chips, and a 10uF across the voltage source for the whole board.

I also bent wires to maximize the distance between 120 VAC wires and logic wires. It solved the problem!

Or so I thought. About every 10 trials, it would screw up (the 1-in-4 sequencer would jump from 3 back to 1, and freeze at 1.) So I tweaked here and there, and finally got it to deliver 25 flawless performances in a row! And on the 26th, it screwed up again.

Ironically, when I went back over my notes from 4 years ago, I found a whole series of :GGGGGGBGGGGGBGBBGGGGGGGGGGG. . . Now I remember: G = good, B = bad. I was testing the system back then, and, would you believe it?--I recorded 23 consecutive "G's"! So I think my problem lies elsewhere, but at this point, if my failure rate is

Dear Rich, OK, so I changed my mind. I'm still hopeful that I could banish forever this annoying 1-in-4 sequencer that goes

1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,11111111 and freezes at 1 (but only when it sends the signal to the SSR to turn on the final green 60 W bulb). I've tried single caps across the whole board, and for each chip, to no avail. But snubbers. . . any suggestion what values of R & C to use, or a site to go to that would have recommendations? Thanks, Bruce

As requested by others, show us your schematics. We're working in the dark without them.

Ed

Hi, Bruce. I'm sorry, but it seems we're in kind of a chicken-egg thing here. To converse about electronics, you need a certain amount of basic knowledge. Since you're reading Forrest Mims, you're getting there (a good thing!). However, in the meantime, it makes it difficult to help you with your immediate problem.

I'll tell you what. First off, I've got several of the Forrest Mims books in storage. So do a few other members of the group (and the estimable Mr. Mims also occasionally checks in on the newsgroup, too). Could you mention which book and page number (or if it's a magazine article, what magazine, which issue and which page).

I can't see that this would be a problem. But if you're not sure where you got the circuit, possibly you could just list the ICs and other components? That would be a big help.

I'm hoping we'll be able to give you a hand here, but we're stuck.

Cheers Chris

I have tried using AACircuit.ICO to draw my schematic, and haven't achieved a very clear result. So I'm experimenting with posting photos on the Net of my circuit. The address below is just one picture, so don't bother going to it just yet. If I find one can actually get to viewing it, I'll put the complete series of photos here, and hope they give a complete idea of my setup. Bruce

Dear Chris,

You are quite a good-hearted fellow to go to such troble for me! I see you posted something a few days ago. I have successfully demonstrated to myself that I can point readers to a photo of the circuit on the `Net (see my post from today.) So I will be assembling a series of photos that will show both the schematics as well as the physical layout of the board (so people could note places where 120 VAC inductive effecs might be a problem.) I'll try to get the photos up soon. Thanks for your patience, Bruce

I'm working on making my circuits easily accessed. Try pasting this on your web browser address window:

No, don't. It wants me to sign on to myspace. Ick.

The first one works just fine here, but it doesn't look much like a 1-4 sequencer. ;-)

Cheers! Rich

Dear Rick,

Thanks for the quick response. I'm still learning how to communicate with this internet thing. Sorry to stoop to using Myspace, but I'm not well-versed in how to do things on the `net. I don't know how to get my pictures viewed by others besides using Myspace (which, I admit, is pretty creepy, but it's the only way I know of at present.)

If the pictures at Myspace are viewable, here's my running commentary on them:

The 1st picture is the schematic for the LM555 timer that sets the clock frequency for the Christmas tree lights. The values shown are not correct, but my choices of R & C give a freq of ~ 1 Hz.

2nd picture shows the combination of CD4013 and CD4001, which ends up outputting 4 pulses in sequence to points A, B, C & D. These outputs then go to BOTH four LED's on the board (shown as 3 yellows, and 1 green), AND four Crydom SSR's that control the four Christmas tree lights: amber, amber, amber, Green.

3rd picture ("drag 1") shows the whole board described above. The SSR's are at the top, and above them you can see, upper left, where the

120VAC hot and neutral lines come in. Directly to the right of that, you can see 4 nails, where the output of the SSR's goes off (green 14 AWG wire) to the four 60 watt light bulbs on the Christmas tree. (The AC power components LOOK, to me, (who knows little about this stuff) to be quite far (~4 cm) from the logic chips.)

4th picture ("drag 2") shows a closeup of the logic chips: 555 ==>

4013 ==> 4001. Note the green .1uF caps that have been added at the power inputs for the chips. This still didn't stop my problem!

5th picture (drag 3) shows an overview of the entire mess: the computer (running Windows 98) is in the foreground, in front of the interface box:

6th picture (drag 4) this is the box that is represented schematically at this website:

This is where I got the idea originally for the whole thing.

7th picture This picture is not directly relevant, but, hey, I''m bragging: I designed this to control the staging and DQ (disqualify) lights. Any car that "jumps the gun" and starts off before the green light goes on, gets its DQ light turned on and their time is automatically disqualified from that run.

I'm hoping this will help anyone who knows enough to have a sugggestion as to why the main starting line board still jumps out of sequence once in a while.

Bruce

If Myspace will work (until I learn better) here's the site displaying my pictures:

--
All of the graphics except for the 555 astable require signing up
with myspace, which many of us are reluctant to do.

I see you\'re using sbcglobal.net as your ISP, and they have direct
access to USENET, so all that you need to do is to get a proper
newsreader, log on to one of the USENET servers they have access to
and then you\'ll be able to post schematics to
alt.binaries.schematics.electronic, which\'ll make it easy for
everyone to see what you\'re talking about.

cap

capacitor

of

I'll try it! Bruce

Ok! That one is clear. Add two components to it: A diode between your + supply and 555 pin 8. (Banded end connected to pin 8) A 470 uF cap from pin 8 to ground.

That may fix it. Even if it does, keep working on posting your circuits. When you can do that, you can get help more easily.

Ed