CAN YOU SEE THE LIGHT SOURCE FOR THE SPEED SENSOR? I LIKE RUNNING NIGHT TIME TIME SCENES.
No, the Mini-Prototype Sound Unit's Infra-Red light source is invisible to the human eye. Your pet
snake or cat might be able to see it.

MY ENGINE ALREADY HAS A CAM SWITCH ON A DRIVE AXLE, CAN IT BE USED?
Yes, engines like a Bachman G Scale 4-6-0 have a cam switch. It can be used instead of the optical
sensor, it makes installation 50% easier.

DO YOU NEED A COMPUTER TO CONTROL THE SOUNDS?
No, the Mini-Prototype Sound Unit has its own which controls the sound reproduction.

DO YOU NEED DCC OR SPECIAL CONTROLS?
No. The Mini-Prototype Sound Unit's tiny computer does all the work. It is designed for "hands free",
user friendly, automatic operation. Some sound units on the market require you to hold down a button
while applying power in a particular (sometimes frustrating) pattern to get the unit to make sound, or
some units may require you to have DCC or a large investment in some other controls to make theirs
operate. Some sound systems look like you need an advanced college degree to operate them.

CAN THESE BE CONTROLLED VIA DCC?
No. The Mini-Prototype Sound Unit was designed 2 years before DCC started to catch on, so the
DCC control capability wasn't designed into the product.

HOW DO YOU CONTROL THE BELLS?
To save cost, space, ease installation requirements and make the operation of the units as easy as
possible...almost all the Mini-Prototype Sound Units have the following control strategy programmed
into them (steam engine example, diesel is similar):

At the first detection of movement one of the following combinations may be given...
1) Safe to Proceed Whistle/Horn followed by the bell with semi-synchronized chuffs
2) Safe to Proceed Whistle/Horn followed by speed synchronized chuffs
3) Safe to Proceed Whistle/Horn followed by the drain cock purges before speed synchronized chuffs
4) drain cock purges before speed synchronized chuffs
5) bell with semi-synchronized chuffs
6) synchronized chuffs

Once the engine is going fast enough, or after 60 seconds, the Bell sound will be disabled until the
engine stops. When the engine is stopped, the tiny computer will change to the next combination in
the listing above after 30 seconds. Some engines perform only some of the above combinations.

WHY IS THE MINI-PROTOTYPE SOUND UNIT THE WAY IT IS...
HOW DOES MINI-PROTOTYPE SOUND UNIT COMPARE TO COMPETITORS?
Small Scale discovered early in development that people were frustrated with complex sound controls
and their cost...make it as low in cost as possible and sound good were many requests.

Certain product specific claims for the Mini-Prototype Sound Unit are...
1). By not having the switches, wires, connectors, etc. and be overly flexible to attempt to please
every hobbyist on the face of the earth, the sound units were made to be very simple to
operate and install for scales larger than N (it get harder for N Scale). We focussed our
product toward the "I want it easy to install and operate" type of customer with considerations
for the N Scalers (if it fits N it'll fit anything larger). All that stuff, to make it ultra flexible, which
can sometimes be helpful, takes up a lot of space, making installation more difficult and
increases cost.

2). As a result of item #1 above, the purchase cost of the Mini-Prototype Sound Unit is by far
lower than any near equivalent competitive sound system for features and size.

example1, in HO you can buy a competitors sound unit that just barely crams itself into
50 ft box car for $210 without installation. If you want, you can get a Ready to Run
HO Box Car for $120 from Small Scale Ry. Co.

example2, the Mini-Prototype sound appears to be the only sound unit to provide
the brake squeals sound upon detected on deceleration.

example3, the Mini-Prototype sound might be the only sound unit to use a light reflective
speed sensor. Although some competitors use an Infa-red sensor, its used like a
mechanical switch, light passes through a hole or doesn't pass through a hole.
That type of sensing approach takes up valuable space inside a motor powered
locomotive. Same goes for the magnet and reed switch (which doesn't work at
high speeds due to mechanical forces, and takes up space). The reflective light
style of speed detection takes up less space, and accommodates a wider variety of
positioning tolerances (mechanical switches have to be more perfectly aligned
with their respective cam or magnet).

example4, we've been told by one customer that after installing a Mini-Prototype Sound
Unit and reading our instructions and Application Notes, they used our documentation
to improve our competitors sound units from their prior kit building efforts. We consider
this a compliment to our documentation and technology.

3). Important parts to make the Mini-Prototype Sound Unit operation prototypical, such as the speed
sensor for chuff synchronization and speed measurement, do not cost extra.

IS THE SOUND LOUD ENOUGH?
For 1.1" speaker and larger sizes, yes. Is it louder than our competitors? Probably. Small Scale Railway
and our competitors all use the same speakers, from the same vendors. There are 3 ways to make the
sound unit louder than somebody else's...(for a mobile sound unit)
1). use a bigger speaker, a bigger speaker cone will move more air...but available space can
restricts installation, making installation more difficult
2). over amplify the sounds, this will shorten the speaker life, damage the speaker, and drain
your battery faster and distort the sound quality (scratchiness)
3). improve the speaker installation so that sound efficiency improves
4). a 1W amplifier is now available for larger scales, as an add on device


ACCURACY OF SOUNDS OR DO THEY SOUND PROTOTYPE?
For the Mini-Prototype Sound Unit, sound quality is everything. Almost all sounds were recorded by
standing within 20ft of the actual prototype. Some inches from the sound source, like the SD80MAC's
bell. Strange sounds from the prototype are included in the sound reproductions...like the ConRail
#5649 SD60 has a high pitched, repetitive "screech" at idle (a dry bearing or oil starved cylinder liner?).
Items like these sounds are classified as "Other Sounds" because we're not sure how to describe them.

CAN RECHARGEABLE BATTERIES BE ADDED LATER, OR MUST THEY BE PURCHASED WITH
THE BASIC BATTERY OPERATED SOUND UNITS?
Nope, if you desire, we provide instructions on how to add Nickel Metal Hydride batteries later.

Small Scale Railway discourages the use of rechargeable batteries if you operate a small
layout where the track voltage rarely exceeds 7V. If you don't exceed 7V, the rechargeable
batteries will never gain a sufficient charge to operate the sound unit (since the Micro-Chuff
and Micro-Diesel require as little as 4V to operate and recharge, they are more flexible for use).

DO YOU MAKE THESE SOUND UNITS YOURSELF?
No, we designed it, but the manufacturing is left to machines at a SE Michigan company.
The PWB's were made in Ohio. The expensive circuit parts are made by US based companies
in SW US. So the US made value add & assembly labor content is near 100%.

WHAT ARE SOME OF THE TECHNICAL SPECS FOR THE MINI-PROTOTYPE SOUND UNIT? size:
3.7" long x 0.6" wide x 0.2" high, without battery, speed sensor or speaker (N Scale 50 box car shape)

power:
5.7V to 12V input voltage at the battery terminal input (can be increased with a resistor)
350mA maximum operating current (100mA typical)
random DC (track voltage) to fixed DC converter, with filter cap. has on board AC to DC rectifier
reverse battery protection on the battery input
a DCC power source greater than 7V is OK

sound:
controlled via software through a 2.5MHz RISC Processor
Sound chip has 3.8KHz bandwidth, with 0.25W maximum output through an 8 Ohms speaker
original WAV source files are 44KHz sample rate with 16 bit resolution
CMOS trigger input to manually control horn/whistle patterns to override automatic defaults

motion sensing:
Reflective Infa-Red sensor 1/8" or closer to the axle, wheel or geared motor output
input available for older "cam" switch sensors, 5 to 10mA contact wetting current
Minimum Input Wheel Rotation Frequency: 1/4Hz (very slow motion)
Maximum Input Wheel Rotation Frequency: 20Hz (very fast)

DO YOU HAVE AN EMAIL ADDRESS? Yes, GL4LEGS@COMCAST.NET
However, due to work loads, internet access, etc. we might not be able to give your mail a quick
response....but we will respond within 24 to 48 hours.