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Author Topic: Got 2K2 sound working with a K-27  (Read 1664 times)
Dave Crocker

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« on: January 14, 2008, 05:18:49 PM »

I have sound working in my K-27 with a Phoenix 2K2 sound card.
The only problem left is that the sensors on the left side (I think) are not positioned exactly correct and I get 4 chuffs and a slight space.

I got my K-27 at the end of last week and spent all my time trying to get the optical sensor to work. The engine was going to run at the Del Mar Worlds Greatest Hobby on Saturday  so I ended up running this weekend with voltage controlled chuff.

The engine performed very well, I was pulling 24 cars around the DelOro layout without any slippage.

The optical sensor puts out a low going high voltage on chuff and the Phoenix expects to have it's high pulled low.
The solution is to install a NPN transistor (Radio Shack 2N2222 works fine) with its collector connected to the Phoenix chuff input (pin 15) and its emitter connected to ground (pin 16 and the K-27 ground (J1-5). Now connect the base to the chuff signal from the optical sensor (J1-7). This inverts the signal so the Phoenix board responds.

The optical sensor has another problem though. It doesn't respond with valid chuffs until the track voltage gets up to 4 volts. The engine starts moving on about 1.5 volts and runs at prototypical speed at about 9 volts so the engine has no sound as it starts. To get around this, as a test,  I installed 5 diodes in series with the motor. These diodes drop about 4 volts and require the track voltage to be above 4 volts before the motor starts turning.

I cut the trace on the plug-in board between one of the chokes and connector pin.
If this becomes permanent, I will have to install 5 diodes in the opposite direction as well or see if I can find an appropriate Zener.

Now I have to take the cylinder area apart and see if the optical sensor board can be moved to get a correct sounding sequence.
If this can't be accomplished, I'll have to fall back on installing magnets.
« Reply #1 on: January 15, 2008, 10:48:58 AM »

Hey Dave here is your fall back......good luck with your venture! Smiley
« Last Edit: January 15, 2008, 10:55:30 AM by calenelson » Logged
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