CEL Design Example
Motorcycle Gear Indicator

Not everything which CEL designs is made for mass production. We also make one-offs, demonstrators, in-house test equipment and other projects which are only ever intended to be made in small numbers.

The device on the left was produced by CEL as a demonstration of how an auxiliary display and accessory controller for a motorcycle might look and operate. It’s wired into the bike’s existing wiring harness and displays various useful pieces of information such as which gear the bike is in, average speed, air temperature and estimated fuel range remaining.

Its internal processor derives this information by timing and counting pulses which indicate road speed and engine rpm. A learning feature allows it to adapt automatically to the signals produced by numerous different makes and models of bike, meaning it would be suitable to build and sell as an aftermarket accessory without the need to stock multiple different variants.

Particular emphasis was placed on ease of set-up by the end user, the process requiring nothing more technical than riding the bike in each gear for a few seconds, so the device can analyse the signals from the bike and learn its gear ratios.

Several units were hand assembled into 3D printed enclosures, and even though it was never intended to be made in quantity in that form, features from it were incorporated into other products which you can buy from a high street automotive parts store today.

On the right is a true one-off – a battery powered motorcycle simulator, which provides power and produces signals (eg. for road speed and engine rpm) equivalent to those available on a real bike. It has controls to replicate ignition, clutch and gears, allowing all the features of its companion device to be demonstrated in a way which is portable and convenient.

Wolf Elec Ltd
Vehicle Intercoms

CEL was approached by Wolf Elec Ltd, a manufacturer of intercoms, security systems and other accessories for specialist and commercial vehicles.

Wolf Elec were looking to supply a voice intercom system as an OEM component for a new purpose built taxicab. A key requirement was that, in addition to driving loudspeakers, new regulations demanded that the intercom support an induction loop for use by passengers who use hearing aids.

CEL developed a novel amplifier which was able to provide clear audio over the entire frequency range, with no more adjustment required than a simple volume control, even when the induction loop was installed in close proximity to the metal roof of the vehicle. Nearby metal normally tends to reduce the signal strength and muffle higher frequencies, which would make the driver of the taxi harder to hear clearly.

Working alongside the customer’s existing design and manufacturing partners, CEL produced a final circuit which was then tuned in the vehicle itself to optimise audio quality. Software algorithms and audio levels were adjusted to give the driver, hearing passengers and hard-of-hearing passengers a clear, unobtrusive experience.

The design also incorporated software features which allowed it to replace several different older intercom PCBs in other applications, including ones on which components had gone end-of-life and were becoming increasingly hard to obtain.

The finished product is now in mass production, and next time you ride in a taxi, you may well find yourself using it without even knowing!

Reventec Ltd
Torque Sensor

CEL was contacted by Reventec Ltd, a manufacturer of sensors which are used by the professional motor racing industry, as well as in other applications which demand high reliability at elevated temperatures and under severe vibration.

Reventec was looking to produce a strain gauge with a 0 to 5V output for measuring the torque applied to the steering column of a racing car. Previously they had been buying in an amplifier from a third party, but it was quite expensive, too large, and required adjustment using a screwdriver which meant it could not be fully encapsulated to protect it from vibration.

CEL designed a prototype circuit around the Analog Devices AD8557 digitally programmable amplifier IC. This device can be programmed to adjust its gain and offset without the need for a physical potentiometer. To control this device and allow it to be adjusted easily, CEL developed software for a Microchip PIC which presented a simple command line interface that could be used via terminal software on any laptop.

The CEL software included a self-calibration facility, so the previously time consuming and fiddly process of adjusting out the zero offset was replaced by a single command taking just moments to execute.

The hardware was first prototyped on stripboard, allowing it to be debugged and demonstrated before committing to a PCB. Finally the board was laid out and sent off for manufacture, with the final design being just 18x25mm.

As well as all the CAD data and source code, Reventec was provided with full documentation describing how the board works, how to connect it up, and how to adjust the gain and offset for any given application using the serial interface.

In this case a clear understanding of the needs of the application resulted in a simple, inexpensive PCB which was quicker to assemble into a finished sensor than an off-the-shelf board, as well as being more robust, accurate and versatile.

Firestone Technology Ltd
Wireless Thermostat

Firestone manufactures Dragon Bench, a heated outdoor seat intended as an energy-efficient replacement for patio heaters outside bars and restaurants.

CEL had already designed a simple thermostat to regulate the temperature of these heated bench seats, and so was the natural choice when Firestone wanted to upgrade the system to permit centralised monitoring and control of multiple units from a single location. Their requirement was to have a device behind the bar which would be able to set and show the temperatures of all the heaters, turn them on in time for dinner service and off at the closing time, and indicate any faults that required attention.

Working together with software engineers at Firestone, CEL developed a smart thermostat around a Zigbee wireless network. The Zigbee standard was chosen because it forms a ‘mesh’ network, in which any device can communicate with any other by automatically routing traffic via intermediate devices. This would mean that benches could be spread over a large commercial outdoor space with no need to have all of them within the radio range of the bar.

With an eye on ensuring the system remained trouble-free and reliable, features were included to secure it from unwanted radio interference, whether benign, malicious or just a nearby neighbour with the same kit.

For simpler installations with only a few benches, the CEL thermostat also included an LCD display, buttons and a real-time clock, so it could be programmed to switch on and off at different times according to a weekly schedule. The option was provided to omit the wireless module on these units to save manufacturing cost.

The finished product was a true collaboration between Firestone and CEL, with CEL providing electrical design, specifications and firmware, and Firestone taking care of the mechanical design, the central controller and the heated benches themselves.