Dave's clock, from Detroit with glow. - Page 1
Forum section: electronics / projects

author: neo
author_rank: Super Contributor
timestamp: June 22, 2017, 12:50:19 am
content: From Russia with glow 2.0, this is not a build log instead this is a continuation of a previous much older post. The clock now is completely functional running off of mains frequency for the clock.Chips used,1, 4068; 1, 4081; 1, 4069; 1, 4013; 1, 4023; 1, 4012; 1, 4017; 5, 4026.Also to quote Dave, you cannot make a 4026 skip one due to lack of access to internal circuitry, i did it with external logic. The only differences from the original post are that it actually works, i know why it works, and the display is from a 1972 Chrysler car radio. Can provide a full schematic on request. Pictures coming soon.Special thanks to: Digsys and Ian M.

author: neo
author_rank: Super Contributor
timestamp: June 22, 2017, 09:31:34 pm
content: Pictures.

author: neo
author_rank: Super Contributor
timestamp: June 22, 2017, 09:33:18 pm
content: More pictures.

author: neo
author_rank: Super Contributor
timestamp: June 26, 2017, 12:56:08 am
content: The last pictures. I really expected more conversation over me making a 4026 count 1-2-3-4-5-6-7-8-9-0-1-2.

author: neo
author_rank: Super Contributor
timestamp: June 27, 2017, 05:03:52 am
content: My clock has a tens of seconds display and i am feeding 10hz into it but it appears to be running a hair fast, a minute a day. Anyone got any clue why?

author: BrianHG
author_rank: Super Contributor
timestamp: June 27, 2017, 05:34:07 am
content: Quote from: neo on June 27, 2017, 05:03:52 amWhere are you getting your 10Hz from?

author: neo
author_rank: Super Contributor
timestamp: June 27, 2017, 12:34:28 pm
content: Mains frequency divided by 6, i have my frequency counter strapped to it as a experiment to see if it does anything odd but it remains at .0100 kilohertz, the finest range of my frequency counter reads in kilohertz.

author: neo
author_rank: Super Contributor
timestamp: June 27, 2017, 01:39:55 pm
content: My best theory is that i have a occasional slight ripple on the mains frequency, given that i live in the country about 20 miles from the plant.

author: BrianHG
author_rank: Super Contributor
timestamp: June 27, 2017, 10:45:36 pm
content: Show me you mains/10 circuit/schematic filter/amp, including transformer voltage & a scope shot of the mains signal entering your first logic gate & entering the /10 counter.

author: neo
author_rank: Super Contributor
timestamp: June 28, 2017, 06:08:28 am
content: Quote from: BrianHG on June 27, 2017, 10:45:36 pmA scope shot will be a challenge for two reasons, A) it is an analog scope and my camera has a hard time taking pictures of it, B) currently the clock is undergoing a test to see how far it drifts in a set period. I didn't include 4017 divide by 6 because it really is dead simple, only way it could go wrong is if it is a dodgey chip.

author: BrianHG
author_rank: Super Contributor
timestamp: June 28, 2017, 06:47:24 am
content: This can be something easy enough to try:Coming out of the transformer, try a 1k-10k resistor feeding into a 0.1uf cap to gnd, then continue onto your existing 10k resistor.LED and fluorescent lamp ballasts add some repetitive nasty high frequency spikes during the AC sine wave and we want to smooth out the AC back into a rounded sine wave before you amplify and square it out.

author: neo
author_rank: Super Contributor
timestamp: June 28, 2017, 07:06:20 pm
content: Quote from: BrianHG on June 28, 2017, 06:47:24 amWhy do led and fluorescent ballasts do that? Would a very cheap tiny transformer be subject to the same thing? Also i tried to take some pictures of the scope, had to use video to capture the square wave.https://youtu.be/y2H8s-wj8p4clock countinghttps://youtu.be/qluCBpDd_Ts10 hzhttps://youtu.be/GEwN7nOiAf460 hz

author: BrianHG
author_rank: Super Contributor
timestamp: June 29, 2017, 01:13:31 am
content: Quote from: neo on June 28, 2017, 07:06:20 pmTheir ballasts convert the AC to DC with simple 4 diodes + cap, then have a switching supply at xx KHz to drive the led or HV for the fluorescent. The current spikes at DC rectification make it back onto you AC mains.Remember, these diodes are sitting on the mains without any extensive filtering like a higher quality computer PSU with good filtering or power-factor correction circuitry. They hit a few 100 ma on the main when the cap is getting charged as the voltage goes up on each cycle, even if the average overall current draw may be 10 or 20 ma. Doing this in a linear supply, the transformer really limits that 'sharp edge' blow from going back to the mains.Worse, some fluorescent lamps leak the switching supply's KHz right back onto the mains as in my house, my old Sony clock radio went fast by a few minutes a day once I switched over to fluorescent lamps 15 years ago. At that critical switch-over point, the CMOS clock counter would occasionally count more than 1 because of the fine 30-40KHz noise in the AC. A signal which just made it through the radio's AC transformer by just enough to count an extra cycle around 7200 cycles in a day out of 5184000 in 24 hours.

author: neo
author_rank: Super Contributor
timestamp: June 29, 2017, 01:20:20 am
content: The capacitor you recommended seems to really make a difference i set it at noon and the count is still accurate.

author: BrianHG
author_rank: Super Contributor
timestamp: June 29, 2017, 01:22:55 am
content: The same trick fixed my Sony alarm clock radio.As you see in your scope shot, that knee/bend in the AC waveform right at the crucial clock transition voltage has been smoothed out to a nice rounded sine-wave.

author: digsys
author_rank: Unknown
timestamp: June 29, 2017, 01:58:38 am
content: Wondered why my name came up at the top :-) ... did you ever get to play with the mercury relays?Looking at your pictures, I hope you never have to service it :-) Great effort on your first try btw ! I hope you continue.

author: neo
author_rank: Super Contributor
timestamp: June 29, 2017, 02:15:29 am
content: Quote from: digsys on June 29, 2017, 01:58:38 amYea i did play with them some though once i switched over to mains frequency the transistors made more sense. It is actually quite easy to service just identify the problematic block and then redo the entire block. For example i did it in steps, first with simple logic like #6 reset then more complex like #13 reset and subsequently the am/pm and finally the part that makes the hours tick once if 00 is detected. As for the display wires they are a pain in the neck but doable, i had the 4026 chips put on pcbs so that the relevant connections are arranged in an order that makes sense with the 7 segments going down to board in order. The board is huge at 18 cm by 30 cm and the display wires took half of that because i used mostly straight lines for simplicities sake. If i may say so myself i find the circuit that makes it tick over to 1 o'clock upon detecting 00 is almost genius. All of this clock is due to that one display from a 1972 Chrysler it really lit my heels to get something done.

author: digsys
author_rank: Unknown
timestamp: June 29, 2017, 03:57:24 am
content: All good then. :-) On your next project, if there's anything junk... errrr I mean quality excess stock that I have lying about, just post your project here. Same deal as before.This is part of a throw out I had a couple years ago .. and soon time for another one !www.pbase.com/digsys/image/153965548

author: neo
author_rank: Super Contributor
timestamp: June 29, 2017, 08:56:29 am
content: Quote from: digsys on June 29, 2017, 03:57:24 amI actually live off of old junk, this clock for example has parts from 3 separate televisions, a computer, the display is two parts; one is from a 1972 Chrysler radio and the other from a 1973 fast food order box, a stereo receiver that was well dead. For my next project i will need at least a 10 pound heat sink.

author: neo
author_rank: Super Contributor
timestamp: June 30, 2017, 08:51:44 pm
content: it now seems to run a hair slow, losing a second or two a day.