Author Topic: GE 8113 - Time Scan  (Read 7537 times)

Kid Clock

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Re: GE 8113 - Time Scan
« Reply #45 on: July 19, 2014, 06:06:00 PM »
Kid,

I think everyone keeps coming to get that LED schematic you mention in Reply #23 but it isn't there anymore. Maybe you should upload it again... :-()

I've searched my computer, in the past, and couldn't find it... let me up my effort factor... (instead of jacking with Down Bro and Russell...)
« Last Edit: July 19, 2014, 06:17:00 PM by Kid Clock »

Kid Clock

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Re: GE 8113 - Time Scan
« Reply #46 on: July 19, 2014, 11:51:05 PM »
OK, you techno cats... I think this is the deal... (don't burn your house down...) 

The two (opposed) LED's scenario eliminates a "flicker" effect,  (On alternating current, in the US, LED's flash 60 times per second, with the two in this circuit, they alternate, they each flash 60 times, but opposite... while one is off, the other is on... you don't sense the flicker...   Henry would have loved LED's...)

I've got mine running right now... it is sweet.  (....running 24/7 for several years, actually...)

« Last Edit: June 08, 2015, 10:00:25 PM by Kid Clock »

Cyclometer

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Re: GE 8113 - Time Scan
« Reply #47 on: July 20, 2014, 12:28:18 AM »
Kid,

Very nice... thanks for the circuit.


Kid Clock

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Re: GE 8113 - Time Scan
« Reply #48 on: July 20, 2014, 12:37:05 PM »
I even found the capacitors I bought...

http://www.ebay.com/itm/121086715084

I think I got these resistors from the same guy, rated at 3W, extra stout...

http://www.ebay.com/itm/110996345443

The LED's I had laying around... (Hey, I like diddling around with LED's...)  I believe these are directional, focused forward, like a miniature headlight.

Due to the direct feed off of the 120V power supply, the components are a tad bulky, making it difficult to fit in tight compartments.  In this case, there is plenty of room.
« Last Edit: July 20, 2014, 01:11:13 PM by Kid Clock »

Carlo

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Re: GE 8113 - Time Scan
« Reply #49 on: October 14, 2014, 12:08:08 AM »
First of all, I would like to say thanks to Kid Clock for providing the circuit, I would have never thought to do this.
After building this for myself, I found that I needed to understand how this worked and how the values were selected.

I will describe what I found in case this would benefit someone else as well.

From a similar discussion on the topic http://cr4.globalspec.com/thread/13464/Capacitors-as-AC-Voltage-Drop-Components
I found the keyword here is capacitive reactance, basically (Xc) = 1/(2 * pi * f * C) where Xc is the capacitive reactance measured in ohms, f is the frequency (in our case 60) and C is the capacitance.

For our purpose, we want a reactance value that yields approximately 20 mA (the actual value of this circuit is about 21 mA so I will use that).
Using V = I*R we get R = 120/.021 which is about 5714 ohms. Putting this into the above formula we get 5714 = 1/(2*3.14*60*C) simplified as

C = 1/(377*5714) = ~.46 ?F which yields our capacitor selection.

Our resistor selection is based on the mentioned inrush current. To calculate this using the provided resistor value, we are estimating that the peak value is around 150VAC (actual is more like 170 but this works fine). Using these values, we get I = V/R = 150/1000 which is 150 mA, a generally safe value for most standard LEDs.

Edit: Not sure this bit on power is quite right, but this is why I'm not an electrical engineer  ::)
For determining the safest wattage of the resistor we can use the equation for power P = (I^2)*R. It appears that the above circuit is rated for the wattage provided after the initial inrush which seems to make sense as the period of inrush is momentary. Using our average current and calculated resistance we get P = (.02^2) *1000 = 0.4 W
Doubling the wattage as is a good practice yields using at least a one watt resistor. The resistor linked above is 3W making this look to be safe.

A good step by step of this can also be found here: http://www.instructables.com/id/Using-AC-with-LEDs-Part-2-and-make-this-handy-/#step1
« Last Edit: October 15, 2014, 12:58:18 AM by Carlo »

Kid Clock

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Re: GE 8113 - Time Scan
« Reply #50 on: October 14, 2014, 07:16:52 PM »
I even found the capacitors I bought...

http://www.ebay.com/itm/121086715084

I think I got these resistors from the same guy, rated at 3W, extra stout...

http://www.ebay.com/itm/110996345443

The LED's I had laying around... (Hey, I like diddling around with LED's...)  I believe these are directional, focused forward, like a miniature headlight.

Due to the direct feed off of the 120V power supply, the components are a tad bulky, making it difficult to fit in tight compartments.  In this case, there is plenty of room.

Get it?... "in this case"....?  I kill myself... kinda a clock collector's joke... D%D

(BTW, nice backup dialog Carlo.   @@*  Dude!)

Kid Clock

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Re: GE 8113 - Time Scan
« Reply #51 on: April 13, 2018, 10:22:01 PM »
I thought I would resurrect this thread that was popular in the past...

 

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