Large Scale Central

Motor Delay With Voltage Reduction For Sound Enhancement

Electronics Power and Sound
#1

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

#2

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.

#3

I received my re-programmed Phoenix 2K2 to the Galloping Goose. This card is very cool and the goose is different from other sound files. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

At 2.3 volts on the rails, with a charged NiCad, regardless of track polarity, you hear the guy open the the door and close it behind him. Then he starts up the engine. But it takes three tries starting it before it catches and settles in to an idle.

The routine takes a bit over 15 seconds and if you just bring up the power, or start “at power” (e.g., point-to-point), you’ll completely miss it.

I’ll set the circuit to delay about 20-30 seconds. Meanwhile, the adjustable regulator that I got from Bang Goods (thanks again Dave Bodnar) is perfect for this application because I can set the voltage at 2.3 volts, with digital readout, regardless of the track voltage, so long as it is at least 3.3 volts. People are going to love this on the point-to-point. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)

The driver really needs to learn how to drive a stick. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-yell.gif)

He holds the engine in gear way too long, revving it out. Then when he shifts, he grinds the gears terribly before you hear the engine up-shift and the RPM drops back down. I makes a heck of a racket. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-embarassed.gif)

#4

Sounds cool. No pun intended.

#5

He holds the engine in gear way too long, revving it out. Then when he shifts, he grinds the gears terribly before you hear the engine up-shift and the RPM drops back down. I makes a heck of a racket. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-embarassed.gif)

Todd, isn’t that the way most people drive a stick? Either they shift too late, or they shift too early. And them transmissions without a synchronizer can be a real bi challenge to shift if your not used to them.

#6

I found some nice Porter & Blumfield low current, 12 volt 4pdt relays (R40-EI-Y4-V200) (188-190 ohms coils) and paid <$12 for four. These are rated for 2 amps on the contacts, but are nice and beefy, more like a 5 amp relay.

Anyway, the 555 chips has absolutely no problems driving these relays when the voltage to the rails gets to ~12 volts, which is about perfect for my purposes. Recognize there is ~3 volt loss to the relay between the losses from the rectifier and chip.

As it turns out, the entire low voltage portion of the system (i.e., 555 chip and low voltage relay) are not even necessary and the entire circuit is greatly simplified. The reason is that if the track power starts out with a voltage that is under the voltage necessary for the 555 chip to trigger the 12 volt relay, the relay just doesn’t trigger.

And when you ramp up the voltage to a level that would be high enough to trigger the relay (~12 volts), the a/c coupling of the chip to the power supply (the 0.1 mfd cap, now replaced with 0.15 mfd) doesn’t allow this “change” to reach the chip, which will only pass a momentary change such as a power reversal through a relay on a point-to-point system. (There was no way that I could ramp the voltage up fast enough to make the chip fire the relay. Again, perfect for my purposes.

With removal of the second low voltage chip and relay, the part count goes down enough such that a single 555 and a rectifier can occupy a single 14 pin socket and I can now easily use “dead bug” wiring alleviating the need for a perf board.

I’m a happy camper.

#7

I’ve included the revised schematic. Timing is set at 17 seconds using minimal stock parts (i.e., no pot).

#8

The circuitry is done and ready to drop in place. Additionally, the wires have been run between the floor and chassis for track pick-up and to let the relay kill the motor and plugs added. The relay only kills the motor and the as-built lights and smoke are unaffected. Additionally a flashing red LED was added to the rear of the railbus and hangs from the underside of the roof.

I changed the delay timing from 17 to 21 seconds (added 10 mfd) to better differentiate the idle from the start procedure, put a couple ferrite beads in the IC’s supply as well as 0.01 mfd on pin 5 to reduce potential “noise” from the motor and a reverse bias diode on the relay to reduce the BMF to the chip, not that these have been a problem so far. (But it hasn’t run with the motor on yet.)

I also added a 2.5 ohm inrush supressor to the relay contact that stops the motor, making the point-to-point start up bit easier on the internal moving parts.

The entire assembly fits on the floor of the railbus just behind the open doors. You have to look in on an angle to see it.

The speaker was trimmed down and fits up into the clearstory allowing the boards to fit underneath. The relay (raised) portion on the board assembly was put to the side so the hanging speaker clears it without problem. (Note the Motts speaker enclosure.)

Three switches control the operation. One dpdt, center off, turns on the delay feature in the up position. In this position the rear LED only flashes when the motor starts up and bus is sitting, but shuts off when the bus begins to move. In the down position, the delay is disabled, but the rear LED flashes when ever bus receives power. The LED power feeds from the green screw terminal on the relay and running at just 2.4 volts for the sound system to do its start up routine, no resistors are necessary.

The center switch controls the volume of the Phoenix board.

The other dpdt, center off, turns on the Phoenix AND connects the speaker in the up position. In the down position, the Phoenix connects, but the speaker is disconnected. This lets me charge the NiCad directly from the rails quicker because power is not lost to the speaker, and more importantly, I don’t have to listen to it while it charges nor do I need to play with the volume control to quiet it. This doesn’t seem to hurt the sound card either.

#9

Do we get to see/hear this in action?(http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

#10

I didn’t know ther was interest. I will do a YouTube when it is back together.

#11

Great looking forward to that.

#12

Snug as a bug in a rug and working perfectly on the bench. I cleaned it’s section of track today and will try to get a run in tomorrow.

#13

I tried it out today and it works great! Unfortunately, when trying to download the video, the camera didn’t. We’ll try for a video again tomorrow.

#14

Aint technology wonderful?

#15

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!