One MAN Clock

We old timers know this as a MAN. Monsanto and Fairchild may have been first to use the acronym MAN for multi-segment alpha numeric led chip. The 7 segment display you often see. I see some interesting ways to produce the display with relays, flaps, and leds but they all have 4 numeric sections. This is as easy as it gets with only ONE MAN.

To read the hours from the minutes the hours slightly blink while the minutes are steady. I tried to video the effect but the iso keeps trying to change the brightness even though I had it locked.

You can expect an EASY to make clock display. The 7 lens segments snap into the case and have ample room for 3 leds inside. There is a decorative color spacer. Easy to attach 4 switches to set hour10, hour, minute10, minute. I made the code easy to understand and allows for anode or cathode driven leds. The flash rate and display duration can be adjusted too. And some brief history websites.

You need:

any arduino, I like the promini or the nano

printout of the 5 sections.

4 ea 7mm tall button switch

usb female or just wire direct to 5v ONLY

2 or 3 smd leds per segment

RTC DS3231

go to the website http://www.decadecounter.com/ and look under Integrated Optoelectronics in the museum section tab. Some great history there and I got to work with some of it.

It never says who came up with the acronym MAN. And no mention of what the acronym stands for. I just guessed it was Multi-segment Alpha Numeric device. In my photos you can see the MAN-1 in the Monsantos device. I wanted more history and a conformation of the MAN but all searches keep going to the human MAN and never the acronym. So now you know !?

Print all 5 parts and 7 segments. I use any white for the lens. Do not use clear or a light color as the leds will shine through. The lens is super thin so you can change the thickness if you like. The color spacer add a nice touch, black on white, black on red...You can match the switch support but I like the switches as part of the case and not to stand out so I like black.

I used smd 3528 big white leds. Easy to work with and the white case of the led makes the led glow instead of a bright dot of light. Solder to wire, Chines pc board, pc board. Any way you can ... 3 per lens and watch polarity. I tie the anode to 5v and arduino pins are ground. I use 150 ohm resistors on EACH led set.

The switches mount to the support with outer legs facing each other. This allows for a ground wire on one side and the active wire on the other side. The photo of the switches ...the red support has been changed to the white support as the switches now mount left to right.

I glue the usb socket in the rear case.

I am making a floating glass clock and the electronics use 595 to shiftout the on segments. This makes the code easy as you just call a section of the array to light a number. BUT this has only ONE segment so I rewrote the code and tied the 7 segments directly to arduino. No 595 here but the photo shows otherwise.

You may have a favorite RTC and know how to code it so use it. I like the ds3231.

Either RTC please use a Backup cap at least 550uf. I use a diode and 1k resistor to keep it from bleeding back to vcc. This keeps the RTC going at least 1/2 hour without power.

I use only 4 variables in the code hour10, hour, min10, min. If you use another RTC just change the update variables for this.

The switches have a timeout and any time can be set, not just one switch, during the cycle. Because there is only one display a menu or multiple digit dosen't work. So a button for each section of time. This means no AM/PM menu either. The time is set with 24 hr format but the code displays a 12 hr format without am/pm. You could add the dot but is lighted am or pm?

The code does have the call to function "convert24to12" which changes the RTC24hr mode to display 12hr mode. If you want a 24hr mode display just "//" blank out the call.

RTC settings hour10- hour- min10- min or 1-5-4-2 as 3:42 I have put 2-7-4-2 an incorrect time and the RTC will bit shift the 2- 7 (max23 2300 hour not 2700 hour) and shift the 20hour 2 to 0 and the 10hour to 0 or 1 leftover from the shift.

I glue the color spacer to the front with dabs of E6000 and wipe clean. Then check all the electronics work and switches. The hour10 is on the left facing the clock. So buttons are hour10 - hour - min10 - min. One button for each digit of time. I like to wait overnight then small dabs of glue the back case to the square knobs.

This is an easy to modify project. The size I used works well to be seen from across a large room. Yet small enough to fit on an end table. And dosen't use much plastic. Any size reproduction is welcomed. The only unique feature is the way to determine the hours from the minutes. I tried several display tactics. About a month of dead ends. Flashing slower for hours and minutes, Dash "G" segment to flash between hr/min. A dot between hr/min. Long and short on and off times. These only made the display confusing and redirected the eyes. A steady even sequence with a regular beat, as this has, preforms best. When my non geek wife could read the time I knew I got it right !

Thanks for viewing ... I have a few projects in the works so see you soon.

please see my BIG NUMBERS lcd.

oldmaninSC