Delicate Merchandise Handling
The following photo shows the John Allen car that inspired this work. If John’s operators were too rough handling trains, his car “trapped” a ball in the opening at either end of a track hidden in a boxcar, and turned on a red light visible below the car. John declared the red lamp indicated a hotbox on the car’s truck. The mechanism had to be manually reset, by putting the rolling ball back onto the curved track.
This “new” version does not turn on a light, but does “indicate” rough handling by sounding the “crashes” of “merchandise” carried within the car. You can see it in action here:
The heart of the mechanism is a similar arrangement of a steel ball, but traveling on a small segment of N-scale flex track. Instead of brass strips for the end travel switches, I used cheap, tiny microswitches ( http://www.goldmine-elec.com ). You can change the movement "sensitivity" of the car by making the internal track for the ball a more shallow curve (more straight). But one must also take into account grades on your layout!
Basic Construction: N Scale Track segment and Microswitches at each end
Mircoswitch Detail
Assembled Decoder, Sound Module and Speaker
The sound is generated by a small, inexpensive audio module, a DFPLayer Mini module Mini ( http://www.ebay.com/itm/281840041896 ), connected to a trimmed iPhone 5 speaker ( http://www.ebay.com/itm/141745780733 ) without enclosure/baffle.
DFPLayer Mini module Specifications:
Supports Mp3 and WMV audio file types
Supports sampling rates of 8KHz,11.025KHz,12KHz,16KHz,22.05KHz,24KHz,32KHz,44.1KHz,48KHz
24-bit DAC output, dynamic range support 90dB, SNR supports 85dB
Supports FAT16, FAT32 file system, maximum support 32GB TF card
A variety of control modes, serial mode, AD key control mode
Built-in 3W mono amplifier
Audio data is sorted by folder; supports up to 100 folders, each folder can be assigned to 1000 clips
30 adjustable volume levels, 10 levels EQ adjustable.
IPhone 5 Speaker IPhone 5 Speaker cut back
The speaker modifications are easy. First, find only the version pictured (usually listed as iphone 5 or 5C speaker. Then make the following cuts (I use flush cutting side cutters):
In the following picture, you will notice between 12 and 20 0n the ruler, a narrow small opening. This needs to be plugged. I use gap filling ACC glue, and then hit it with a drying accelerator to seal the opening (shown in the rightmost speaker:
Then solder your speaker wires to the two spring contacts. Speaker impedance is 8 ohms. But here is the incredible benefit-- it is good to go into your loco or animation as is! No baffle or enclosure needed. It produces clear and loud sound as good or better than the "sugar cube" speaker shown with its baffle! The little speaker above it is my favorite low cost alternative (I think it is the earphone speaker to a Nokia 630 or 635). It has height, but smaller area. Once modified the iphone speaker is so thin, it fits well attached to the underside of a loco cab roof. That plastic extension (and the one I cut off) is the baffle designed for the iphone. This is the speaker used when you use the speaker phone in the iphone, not the other little one at the top used for the earphone. I demonstrated this speaker in my “Modeling with Sound” clinics with the speaker just hanging in mid air. ...It's one more tool in the modeler's toolbox.
Wheel Contacts
Wheel wipers were added by drilling two small #79 holes in the frame of the plastic trucks and adding Tichy 0.015 phosphor bronze wires for electrical feeders from the rails. Metal wheels were substituted for the original plastic wheel sets.
Metal Wheels and 0.015 Phosphor Bronze Wire Contacts Added
Model Construction Variations
You can use a simple circuit with the DFPlayer module alone shown below, and power it with a small battery, even 2-3 AAA batteries will do. The DFPlayer uses a tiny micro-SD memory card to store the sound clips it will play. In this simple case, grounding “KEY1” or pin 12 on the DFPlayer will play the first file (001.WAV) on the SD card which should be named “001.WAV” and if you have not guessed, the file should be in WAV audio format. You can use any of the free audio editors available on the web (like Audacity) to edit your “crashes” and convert to WAV format if needed.
Battery Powered Stand Alone Crash Car – One Sound Played
I wanted a bit more variety than one sound, and with basic on/off control, so I used the Arduino Pro Mini DCC decoder design described earlier ( https://forum.mrhmag.com/post/sma20-low-cost-17-channel-dcc-decoders-ver-6-01-with-soundtriggered-soundstepperdual-motorled-and-12201920 ). This provided power from the DCC bus, decoder function control, and allowed the Pro Mini to randomly select from 10 (it can be many more) different crash sound clips. All the sounds and the player/decoder sketch can be downloaded here: http://mrhpub.com/files/users/geoffbfiles/SMA21_Downloads.zip
DCC Crash Car Schematic with Decoder and Arduino Pro Mini
The decoder default address is 24. F0 turns the crash sounds on and off. The start up default forces F0 on - not a normal decoder standard. The reason for this is that if the car is never selected (addressed by a throttle) it will operate as normal (sounds on) and stay that way. If you select the address and turn F0 off, the sounds go off.
There are more “features” that could be added, including flashing LEDs for “explosions” inside the car, a red LED to mimic John Allen’s hot box indicator, and alternate sounds, like shouts, or animal sounds. I’ll leave all those as an exercise for other modelers. Note too, that even without the decoder, this provides an outline for modelers to use this low cost setup to trigger other sounds and sequences around their layouts and models. Appropriate comments and suggestions are always welcome.
If you use this, I hope you share your work too. Have fun! ![[smile]](https://cdn.websitetoolbox.com/images/boards/smilies/smile.gif)
Best regards,
Geoff Bunza
