Quoted from Vengeance

My question is what's it for?

I wasn't happy with any of the candle solutions out there for SS. Pinball Pro sells an led encased in resin. GI voltage is AC and therefore you have to put in at the very least a full wave BR to just get them to light and remain on otherwise your going off an opto circuit possibly. Next to the skull pile going through it's animations it's hardly an effect to have two more leds just on. I got a hold of Terry Nelson to see if I could snag one of his boards. Basically he's gotten out of doing them. Terry's board has a nice effect but you can't get it.

Here is his site.

http://scaredstiff.nelsonamusements.com/

My preference was to embed two leds per candle, one orange and one red. I didn't want them flashing, there is enough in that back corner flashing to give you a seizure with skull pile modded, so I elected to have them smoothly alternate in intensity like a glowing flame. This circuit does exact that and in fact I bread boarded the whole thing with a diode bridge and cap to smooth out ripple and hooked it to SS's 5 VAC GI string where it works like a charm.

So at the end of the day I wanted this effect and I don't plan on plastering a bread board to the back of my pf   so I figured now would be a good time to play around with making a board. This board is pretty straight forward. Rectifies the voltage and gives a glowing effect without having to install numerous components.

Of course your solution is perfect, but did you give thought to lo-teching it with any one of the numerous battery driven flickering led candle solutions out there? Or was that just not going to be "stiff" enough?   I use them for halloween effects (much easier than re-lighting candles blown out by the wind...), my first thought would be to just tap into one of the 5 volt DC sources ... it's not like an LED circuit is going to draw enough juice to disrupt  (if you take some precautions).

Yes, before any of this I did look at the $1 flickering candle solution and it was viable too.... with about the same amount of added board work. I wanted to go two colour and more glow than flicker. Besides those things don't fit snugly into the holes provided.

http://www.instructables.com/id/Flickering-LED-Candle/

I would still require a supply voltage, my one of choice is the GI because when you get Scared Stiff the GI goes out and I want the candles off at that time. Optos are still getting power during the mode so using opto power it is not the effect I want. To me the solution is a board with a basic full wave rectifier. The GI runs at about 5.6 VAC. With a simple diode full wave bridge and small cap circuit loss is minimal and I am getting 4.7 VDC with low enough ripple that the LM324 operates.

Got my boards from batchpcb. Turned out great from what I can see.

That was easy. Thanks for the tip delroy666!

Assembled. Unfortunately one of the two boards was lost in the name of science. The damn manufacturer of a transistor reversed the pinouts and caused me to go through some head scratching and board abuses to figure this out.

The purpose of going through the experiment was to learn the process. What I would modify should I do another circuit is marginally increase the drill diameters for ease of assembly, also rather than using transistor symbology I would mark E/B/C so as to allow for substitution for other manufacturers product given the issue I ran into. Not a whole lot of changes would be made but enough to prove to me the merits in prototyping something like this.

The project met it's aim in ensuring I could design, have produced and assemble a working board. I was thinking of doing the translite TZ door mod as a single board next. On that one I would like to have a driver board transistor trip an effect like AFM saucers mod does.

Silly question:

If you aren't doing a lot of duplicates, aside from gaining the experience wouldnt it have been easier to just use a breadboard?

Beautiful...

now how much smaller if it was smt

Very cool!  

I'm sure you'll be getting that C+D from Wayne any day now  

Quoted from machine.slave

Very cool!  

I'm sure you'll be getting that C+D from Wayne any day now  

Lol.

OK - I'm jealous.  How did you figure out the circuit - and why did you choose to use op amps?   Just wanting to learn...

Quoted from Tuborg

OK - I'm jealous.  How did you figure out the circuit - and why did you choose to use op amps?   Just wanting to learn...

The credit goes to Bill Bowden for designing the fader circuit. I didn't get struck by lightning and suddenly arrive at this design. I simply made some adjustments to it and added a rectifier operate from the 5VAC GI circuit.

Here is the theory of operation.

In operation, a linear 3 volt (peak to peak) ramping waveform is
generated at pin 1 of the LM1458 IC and buffered with an emitter follower
transistor stage. The 22uF capacitor and 47K resistor connected to
pin 2 establish the frequency which is about 0.5 Hz. You can make the
rate adjustable by using a 100K potentiometer in place of the 47K
resistor at pin 2.

The circuit consists of two operational amplifiers (opamps),
one producing a slow rising and falling voltage from about 3 volts to
6 volts, and the other (on the right) is used as a voltage comparator,
the output of which supplies a alternating voltage switching between
2 and 7 volts to charge and discharge the capacitor with a constant
current.

Each of the op-amps has one of the inputs (pins 3 and 6) tied to a
fixed voltage established by two 47K resistors so that the reference
is half the supply voltage or 4.5 volts. The left opamp is connected
as an inverting amplifier with a capacitor placed between the output
(pin 1) and the inverting input (pin 2). The right opamp is connected
as a voltage comparator so that the output on pin 7 will be low when
the input is below the reference and high when the input is higher
than the reference. A 100K resistor is connected between the comparator
output and input to provide positive feedback and pulls the input
above or below the switching point when the threshold is reached.
When the comparator output changes at pin 7, the direction of the
current changes through the capacitor which in turn causes the inverting
opamp to move in the opposite direction. This yields a linear ramping
waveform or triangle waveform at pin 1 of the inverting opamp.
It is always moving slowly up or down, so that the voltage on the
non-inverting input stays constant at 4.5 volts.

Adjustments to the point where the LEDs extinguish can be made
by altering the resistor value at pin 3 and 6 to ground. I found
a 56K in place of the 47k shown worked a little better with the
particular LEDs used. You can experiment with this value to get
the desired effect.



A PNP transistor was added to the circuit provide a reverse effect of a second colour illuminating when the first dims. I am still experimenting with various LEDs embedded in clear resin to provide the yellow/red glow I am looking for. Next attempt will be stacking two diffuse square ones in the back and see what effect that produces.

Thanks.  In reality not much is invented these days in my opinion - just refining other ideas.  It is hard to separate "invention" from "development".   Love the look and congrats!