Trying to create a 3-channel ''movie theatre'' marquee chaser

Audioguru again

Joined Oct 21, 2019
6,673
Has an ordinary battery (AA alkaline cells) been used to see of it can power the circuit but the weak little coin cells cannot?
Is the 555 a high current NE555 or is it a low current Cmos LMC555?
 

Thread Starter

SpielbergRules247365

Joined Aug 9, 2022
47
The schematic he posted yesterday shows an LMC555. The old NE555 will cause 400mA (!) shoot-through current spikes each time it switches and the tiny coin cells battery cannot handle that.
The actual part is a Ne555P. The LMC... was brought up by EasyEDA. I just didn't get to change it. Thanks! :)
Apologies for the confusion on the type of 555. It's actually a Ne555P, not N. The LMC was brought up by EasyEDA. I just didn't change it - only grabbed it the footprint.
 

Thread Starter

SpielbergRules247365

Joined Aug 9, 2022
47
Interestingly, after following the suggestion of reordering the LEDs in 4 groups (2 sets of 2 in series, 2 sets of 3 in series, then all in parallel,) with some resistors, it has been running for almost an hour (as of the time of this posting). I think that grouping was the trick!

The LED's are brighter now (thanks to the BC547 suggestion,) and it looks great! I'll repost the schematic with the correct values when I get it done.

I will put fresh batteries in and then see how long it stays on. It really only needs to be on one time for maybe 10-12 hours, so anything after that is "bonus time." The user can change their own batteries if desired.

As mentioned early in the thread, I was very heavily into digital from 1979 to the mid to late 90s, then life took over for over 3 decades, and I had forgotten a major portion of the finer details and troubleshooting skills.

Thank you to EVERYONE who helped this old man bring back some great memories and completing a great project! You are the true gurus!

When I get the circuit boards made, I'll post some pictures and a video of it running if allowed.

Thank you all again!

Mike
 

dl324

Joined Mar 30, 2015
16,845
I could have sworn it was an NE555N, but t is actually a NE555P
The only difference between N and P is the package.
the CD4017B is actually a C4017BE
Same here. The former would be in a ceramic package and the latter in plastic. No functional difference.
As mentioned early in the thread, I was very heavily into digital from 1979 to the mid to late 90s, then life took over for over 3 decades, and I had forgotten a major portion of the finer details and troubleshooting skills.
I started out as an electronics technician in the mid-70's and switched careers in the early 80's. Didn't get back to it until around 2005 (as a hobby). Fortunately, I recalled much of what I learned 25+ years earlier.
 
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Thread Starter

SpielbergRules247365

Joined Aug 9, 2022
47
The only difference between N and P is the package.
Same here. The former would be in a ceramic package and the latter in plastic. No functional difference.

I started out as an electronics technician in the mid-70's and switched careers in the early 80's. Didn't get back to it until around 2005 (as a hobby). Fortunately, I recalled much of what I learned 25+ years earlier.
Good to know both points on the chips and very cool that you recalled.. I should have contacted you 25 years ago! :)
 

dl324

Joined Mar 30, 2015
16,845
Good to know both points on the chips and very cool that you recalled..
I didn't recall. Surface mount devices were used back in the 70's, but most components were still through hole. I looked up the info in the datasheets to be certain. This is a peer reviewed site and sometimes the nit picking can get pretty extreme.

Unlike most other sites, this one lets you ignore members who happen to rub you the wrong way.
 

Thread Starter

SpielbergRules247365

Joined Aug 9, 2022
47
I didn't recall. Surface mount devices were used back in the 70's, but most components were still through hole. I looked up the info in the datasheets to be certain. This is a peer reviewed site and sometimes the nit picking can get pretty extreme.

Unlike most other sites, this one lets you ignore members who happen to rub you the wrong way.
I meant good that you easily recalled things from that long time ago.

And I absolutely agree about nit-pickers. Although (so far) I haven't experienced it on this forum since this is my first post,) but in SOME cases, I'd rather have more info than needed than not enough, especially since my memory... well you know..

So, an update from today's "Thank you" post. I started with fresh batteries at 10:00 am EDT. The 2 sets of 2 and 2 sets of 3 were of equal brightness before I hooked it up to the rest of the circuit.

As the circuit ws running, I noticed the 2 sets of 2 started getting slightly dimmer than the 2 sets of 3. Then I had to go help mom for a bunch of hours.

When I got back, the 2's were pretty much gone but the 3's were still going strong and bright.

I just need to tweak the resistors on the sets to balance it out.

The resistance formula I was given worked perfectly on paper (well, on my cailculator...)

But in reality, just some tweaking will do the trick.

But other than that, this was a great [re]learning experience and thank you for all your help!

As mentioned, once I get it finalized and the boards made, i'll post pics and vids and a schematic when I get it done.

Thank you!

Mike
 

Thread Starter

SpielbergRules247365

Joined Aug 9, 2022
47
Want to share your resistance calculations? I’d be curious what you did.
Sure!

I put in fresh batteries that totaled 9.92V.

For the "2-String":
R = (Vss - Vftot) / Aled
R = (9.92 - 4) / 0.02
R = 5.92 / 0.02
R = 296Ω (Rounded to 330Ω)

For the "3-String":
R = (Vss - Vftot) / Aled
R = (9.92-6) / 0.02
R = 3.92 / 0.02
R = 196Ω (Rounded to 200Ω)

When that early test showed a bit dimmer output after a short while, I dropped them from 200Ω to 100Ω. As mentioned earlier, when I got back about 6-7 hours later, the 3's were still going strong, and the 2's were pretty much out.

Tomorrow, I will experiment with different values until it matches.

Thanks!

Mike
 

Thread Starter

SpielbergRules247365

Joined Aug 9, 2022
47
You must measure the battery voltage only when the circuit is running.
Thanks for that great tip.

It seems that there are more replies than I am getting notified about. Someone also asked me about possibly using AA batteries (could have been you).

There's so many awesome replies here I think I need to pull it all and copy it to Microsoft Word or something because think I missed some stuff...
 

Thread Starter

SpielbergRules247365

Joined Aug 9, 2022
47
What I said was that CR2032 batteries are very weak and tiny little things.
Oh ok :) Gotcha... The first version of this project before the transistors were added ran for literally almost 3 days. After about 1-1/4 days, they started dimming. but I was surprised it lasted THAT long. Of course only 10 on at a time for quick fash.
 

dl324

Joined Mar 30, 2015
16,845
When that early test showed a bit dimmer output after a short while, I dropped them from 200Ω to 100Ω. As mentioned earlier, when I got back about 6-7 hours later, the 3's were still going strong, and the 2's were pretty much out.
Post a schematic of how you have the LEDs configured. What is the runtime you're after?
 
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