# Motor Delay with Voltage Reduction for Sound Enhancement



## toddalin (Jan 4, 2008)

I decided to have a Phoenix 2k2 reprogrammed to the galloping goose sounds and install it in my AristoCraft railbus. The railbus runs point-to-point automatically with no intervention.

The Phoenix goose card is way cool in that in addition to engine and horn, when the power is first applied, the operator is heard to crank over the engine. Obviously, this makes no sense if the railcar is instantly in motion.

To address this, I created a delay circuit using a 555 timing chip. When the railcar receives track power, the chip throws a relay that disconnects the motor from the power, and sends a reduced voltage to the sound card so the sounds of the railbus starting and idling will occur for a preset time before the railbus actually moves out.

My "breadboarded" circuit will delay the motor from ~1 to ~55 seconds before the bus moves out. I'll "board" the circuit after I get the Phoenix reprogrammed, so I can get the start/idle voltage correct. Total cost for the components was nothing (I'm fairly well stocked), but would would be under ~$5 using Internet available parts (e.g., Allelectronics).

http://www.phoenixsound.com/wav/goose.wav


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## toddalin (Jan 4, 2008)

I decided that an enhancement to the circuit was in order.

As initially planned, when the engine would receive >~12 volts or more, as when it runs point-to-point, the delay circuit would engage and the sound card would receive a reduced voltage while the motor was disconnected. This would then produce the sound of the engine starting and idling for a few moments before the railcar drives off. It would also delay the start of the railcar from other trains elsewhere on the railroad that are under control of the same reverser that start instantly when current is reversed.

But if the voltage is ramped up, rather than running in typical point-to-point mode, the railcar would start and accellerate until the voltage was high enough to kick the relay. The motor would then disconnect and the voltage would drop to that required to produce the sound of the engine start and idle before taking off again. Not an ideal situation, but it can be overcome by switching off the circuit when not running point-to-point.

Not good enough!

I decided that with some modification to the circuit, it could be made so that if a voltage of over say 12 volts was instantly applied, as in point-to-point operation, it would do its motor delay with start-up sounds, but if the voltage is ramped up, this is ignored and the train behaves normally.

This is addressed by using a second 555 chip to throw a low voltage relay that will kick before the high voltage relay if the voltage is ramped up. When the low voltage relay kicks, it disconnects the windings from the high voltage relay so when the voltage gets to that point, the high voltage relay can't throw. If the high voltage relay doesn't throw, the motor and sound system remain connected as normal. 

The trick is then to get the high voltage relay to throw at 12 volts without the low voltage relay also throwing simultaneously and disconnecting it. To do this, we delay the closing of the low voltage relay by a few milliseconds. This then gives the high voltage relay a "head start" and as it begins to throw, it disconnects the low voltage relay's windings so that it can't throw to disconnect the high voltage relay.

The schematic is included.


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## toddalin (Jan 4, 2008)

I ended up simplifing the schematic and built the unit. (The enhanced circuit turned out to be unnecessary.) Simplifing the schematic gave me another pole on the relay so now when the guy goes through the start-up routine, a red LED flashes on the rear of the railbus until the motor kicks in and the train starts to move. When the delay is disabled, the LED can still be switched to flash continuously when the train receives power. This is powered from the low voltage board at 2.4 volts and no limiting resistors are necessary.

Also, to let the sound set into a notable idle before driving off, the timing ws increased from 17 to 21 seconds by adding 10 mfd in parallel with the 47 mfd. The speaker was trimmed to fit mainly within the clearstory to provide space underneath for the boards. The tall pieces are located to the sides to clear the speaker.

I've installed it and it is working perfectly on the bench. I'll see if I can run it on some track and get a video tomorrow.


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## toddalin (Jan 4, 2008)

When your Wife thinks it's Cool, you're on to Something!

I did pics and a video of the enhanced circuit in operation both without and with the enhancement. The addition of sound is always nice, but this is just plain cool!


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