When marketing and selling a product, you need to concentrate on the broadest features that would appeal to a wide range of potential customers -- so you don't get a lot of time, space, etc. to talk about the detailed engineering that has made it into the product.
When talking about Mongoose to more technical folks, it was clear that we have a number of features that were thoughtfully considered and incorporated into the product, and appreciated by technical users. These require too much explanation, or might not be clear to the average reader, to call out as main features. I had a number of calls and exchanges with technically savvy users that were surprised we thought about this many details, so I went ahead and decided to write about them here. These are features of the system that are invisible to most users, but are important parts of the design that go beyond the communication features, battery life, and ruggedness that appear in other descriptions of Mongoose.
True Resistance Measurement - Mongoose integrates true resistance measurement of every output. They can be read at the field unit itself on its LCD display, or remotely from the firing computer. Having it integrated means that everything is in its final firing configuration while you test, not using some external board that you need to unplug before firing. Too many problems occur in other systems after continuity testing because plugging and unplugging cables is one of the biggest sources of continuity problems.
Resistance measurement can tell you a lot about your circuit. You can spot shorts easily. In series-wired circuits, an experienced operator can actually tell if the right number of matches are in series by looking at the resistance, and it gives you immediate feedback as to the quality of the connection even if you have to fire through long cables or shooting wire. It can even help you find those ematches where the composition has come off the end of the ematch, where the resistance tends to be high because of corrosion on the exposed wire.
The continuity circuits never send more than 18ma though the circuit and never longer than 15ms, which is far below the lowest no-fire currents. It has fail-safe design to limit current to no-fire levels even if components fail. The resistance measurements can be made even if the system is already armed. Going into continuity mode locally at the unit itself immediately disarms it if armed, and refuses to accept any commands from the computer until the operator exits continuity mode for added safety.
Current Limited Outputs - The outputs are independently current limited to manage power better, provide more even heating to the e-match bridge wire, and protect against short circuits. The output current is limited to about 2.4 amps per output, which is more than enough to fire ematches reliably, even when wired 15 or more in series at a time. Typical professional ematch "all-fire" currents start at 600ma, and pretty much all of them guarantee reliable series firing at 1 amp.
This feature gives us the ability to fire more outputs simultaneously, and allows one to fire into short circuits without causing damage or affecting how much power is available to other outputs which are also energized. Some systems can effectively dump all their energy into a short circuit, and other outputs energized at the same time may not fire. Our power management guarantees that there is plenty of power to fire many outputs truly simultaneously.
True Simultaneous Firing - We dedicate firing circuitry to *every* output. Some wireless systems, such as one popular one from Europe, actually fire 48 cues by switching 6 positive lines and 8 grounds to achieve 48 shots. In a matrix arrangement like this, it is impossible to arbitrarily energize any combination of outputs at the same time, since only 1 positive and 1 negative can be energized at a time. Systems like this may try to mimic simultaneous firing by pulsing each output one after another quickly, but it is not really simultaneous shots as envisioned by a choreographer. Also matrix systems can fire unintended effects if any of the different grounds or positives short together if heat melts the insulation of ematches (that never happens in a show, right?) and the conductors of different matches touch each other.
Extended and Configurable Firing Time - Some systems only provide the firing pulse for a short period of time (like 10 ms) to fire an ematch. Our default output time is 100ms and we can configure it using our USB settings to over 2 seconds. This is important when firing in very cold environments or when using matches that take longer to heat up to firing temp (like some ematches that do not use pyrogen). Mongoose's outputs can also be used to reliably energize relays and other triggers that can be connected to other pyrotechnic, electrical, or entertainment effects.
Electrostatic Discharge (ESD) Protection - All outputs are ESD-Protected to 2000 volts, so that you aren't going to accidentally zap them when handling them. Any ematches plugged into a unit are also essentially shunted until use.
"Air Gap" Safety - Our Mongoose field units include a relay that positively disconnects all firing voltage from the output electronics until the unit is armed. Some people raise an eyebrow at the use of a relay, but an air gap safety mechanism is the best way to prevent dangerous voltages from being delivered at unwanted times, and is required in critical situations like blasting. Air Gap means that there is actually air between you and the firing voltages, and not just some transistors that may fail. Unless the relay is positively energized, there is literally a break in the circuit for safety. And no, we don't use latching relays that can be affected by vibration. These are high quality relays good to about 1 million arming and disarming cycles.
Firing Voltage Dump - The Mongoose unit boosts its internal battery voltage to 24 volts for reliable firing with many ematches in series or over very long firing wire runs (over 500 ft). In addition to the Air Gap relay, we have a dump resistor that discharges all the firing voltage within 2 seconds after disarming.
Low-Cost RC Batteries - The Mongoose system is designed to accept rechargeable Lithium-Iron chemistry battery which is used in many radio-controlled systems like race cars and drones. We use 6.6V 2S style batteries. These are much safer than traditional LiPo batteries (which you hear about in the news reports when phones and computers burst into flames) and in a pinch can be replaced since we use the same connector as many Radio-Controlled vehicles and drones. However the base battery will last for many years before replacement is necessary.
Extreme Battery Life - The power management of the system was carefully designed to maximize power efficiency. Even when fully armed, the batteries last over 17 hours. This is useful for the long events (like football games) where you need to be ready to shoot at a moment's notice. In other cases, crews simply finish loading and continuity checking and leave the units on in the field, where they simply wait for the main control computer to contact them. The firmware upgrade this spring will extend the standby time of the field units to weeks, not hours or days. This is useful when you need to have pyro controllers installed into the rigging of concerts and events.
Flexible Recharging - The recharging port can accept voltages from 8V to 14V to recharge the LiFePO battery. We sell 8V chargers, because these waste the least amount of input voltage as heat, and allow faster charging. But in a pinch once can even use 12V car batteries as chargers with an appropriate 2.5mm connector (center pin is positive and collar is negative). Even if you neglect a unit and let it discharge completely, adding a charger for a few minutes will bring it back to life, as it can also function while the charging source is plugged in.
Millisecond Timing - The Mongoose units provide verifiable millisecond timing for precision timed sequences. These are so accurate that they can reliably simulate things like A10 "Warthog" strafing runs, where a shot needs to be fired every 16 thousandths of a second, as seen in this video.
Non-Interference of Multiple Systems - Mongoose's unique communications technology not only provides long range reliable communication, but it allows separate systems to operate in the same vicinity with absolutely no impact on other systems in the area. If two or more systems are set to different Mongoose channels (up to 53 in the US), the systems will be completely independent. They will have no issues waking up or communicating with each other when their control computer comes online, and they have no chance of affecting each other in terms of arming or firing. This makes it easy to have multiple systems in the vicinity for concerts where safety dictates multiple control stations, or setting off real time effects (like for races) while there is a post-race display already set up in the background.
Simple Configuration and Firmware Upgrades - The Mongoose systems can be configured and upgraded through the use of a simple USB flash drive. There are no extra programming dongles to buy and no need to disassemble the unit. A simple set of button pushes allows you to upgrade a unit using an encrypted firmware file you simply download from our website and load onto the flash drive. We also strive for backwards compatibility, allowing units with different firmare levels to operate properly together in the same show.
Wrapping it Up
There are a lot more design choices that we made in Mongoose that are even more detailed than these, and even some unannounced features on existing units that will be enabled with future firmware upgrades.
The interesting part of our journey thus far is finding out that several engineering-minded folks have independently verified these things to satisfy their natural curiosity. We've had reports that units have been put on test benches and tested for timing, current levels, etc. These folks have developed an appreciation for the thought we've put into the system.
We intend Mongoose to be a platform for the future, that will grow along with our customers. You may see another blog like this on the software features that are very powerful, which are not apparent in our everyday marketing materials. But you don't have to worry that they are magical, since we have over 500 pages of documentation covering the system. You can be up and running with the system in 30 minutes doing simple shows, but we also have the capabilities to support lots of unusual situations and sophisticated show management that will be the subject of another article.
We also have several new product additions to the Mongoose family coming soon! Stay Tuned!