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another 4017 decade counter question

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charlie_r

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Trying a bit of older tech, and wanted to make sure I had it right.

Am wanting to power a matrix of LEDs using a few 4017 decade counters, and see just how low a power consumption I can keep it, using cheap parts.

This would be used as a general wash type of light, for a small closet or camping tent.
small, lightweight, and fairly long running.

I know using a micro, be it atmel or pic would be the best, and will be doing that as well just for comparison. Use of a micro would probably be the least expensive route, and the way I've put this together, would require only minor changes.

Circuit explanation (see attached schematic):

JP5: pin1: 6V in from NiMH battery pack for powering the 4017s
pin2: 3.6V in for powering the LEDs
pin3: clock signal from 555 timer
pin4: ground or common

JP1, 3: row 1 - 7

JP2, 4: column 1 - 21

IC1, 2, 3: ULN2003 sink arrays, for the columns

IC4: rows driver, with PN2907A to power the rows

IC5, 6, 7: columns driver set

The question I have is do I have it right for strobing individual LEDs?

Clock signal would be about 200Hz, with a duty cycle of 1.5% [Will this be high enough?]

Clock signal comes in to IC5, and is cascaded through the columns. CarryOut from the last column driver goes to the clock in for the rows, advancing to the next row.

Link to the **broken link removed**.

Closer detail of **broken link removed**.

Am I missing something, like pull-up or down resistors etc?

Thanks!
 
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What is "a wash light"?
You saved your schematics as very fuzzy JPG file types instead of very clear PNG file types so we cannot see any details.
Does your circuit simply blink one LED on at a time so most LEDs are dark most of the time? Why? Strobing LEDs at a frequency that is high enough so they do not appear to be blinking results in an average brightness that is very low. LEDs are dimmed by reducing their duty-cycle.
 
hi Charlie,
Repost your circuit, it seems to have been deleted.??

I think a 'wash' light is a low level light source that provides low ambient light over a 'wide' area, IIRC its a theatre stage term for lighting.??
 
hi Charlie,
Repost your circuit, it seems to have been deleted.??
The words "schematic " and "control section" are highlighted in hard-to-see blue and have links to the schematics that are posted somewhere else. They are too fuzzy to see details.
 
will repost links to png.

Ericgibbs, you are correct with your description of wash light.

Audioguru, the idea is to get a usable level of light without a huge current cost. I'm not looking for 500+ lumens (60watt bulb is rated at 710), just enough usable light for safety.

Links:

**broken link removed**

**broken link removed**

**broken link removed**

If needed, I will overvolt the LEDs to get a better voltage rise rate within the on time. I have experimented with that, and at 25% overvolt, the LEDs are apparently "seeing" just under their nominal design spec.
 
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LEDs work with current, not voltage. Higher current makes them brighter and hotter. The heat is wasted energy.
Your circuit has many ICs without a part number and the power supply voltage is not shown so we don't know what limits the current in the LEDs.
Your circuit probably turns on one or a few LEDs at a time at a high frequency so they do not appear to blink. But then the current must be fairly high for the LEDs to appear not bright and there will be a lot of wasted power.
 
Audioguru, please check your glasses, the part numbers are there. Also please reread the OP. All I'm looking for here is to confirm that I have everything I need in the circuit. Meaning, do I need to tie unused pins to V- or V+ through pull up or pull down resistors, and possibly add protection resistors to any inputs such as on the CD4017, ULN2003 or BC327.

I have tested with 555 and single LED, and multiple LEDs. So I know what I need to do to get the light output I desire. I know LEDs are a current driven device. Suffice it to say that I can handle the brightness issues adequately for my purposes.

Single LED test: 3.6V white 5mm LED, driven from pin 3 of 555, at 7.2V. 1kHz freq, .7% duty cycle. NiMH battery pack lasted 5 days before voltage dropped to 5V. I don't expect that kind of performance out of this circuit, due to the increased complexity. More parts, more watts used over time.
 
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Audioguru, please check your glasses, the part numbers are there.
The text on your schematics is just a tiny blur. I zoomed in 3 times and 4 times the size to try to read it.
 

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  • LED array ICs.PNG
    LED array ICs.PNG
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Sorry, those look fine on my monitors. I don't know why they are coming out so blurred on yours. Anyway, the left thumbnail in your post is the CD4017, the right is ULN2003
 
It looks like you saved the schematic as a lossy JPG file type then converted it to a PNG.
But you must save the original as a PNG.
 
Actually, I used winsnap 3.1.0 to take screenshot. will try it again with something else.

I did save original as .png

Edit: doesn't seem to matter what I use, or what I save it as. Still wants to pixelate the text.

Do you have eagle 5.7 or better? That is what these are drawn in. If so, I will post the original .sch file.

Edit2: **broken link removed** WARNING..very large file size.
 
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