We at RM Frobisher are often asked how we produce quality products at such low prices. The short answer is:
‘We do it by design.’
The longer answer is that we have years of experience in the design of electronic systems to measure difficult analogue signals in real world situations. In addition to our electronic design skills we draw on our engineering background to design equipment that will stand up to rugged use and that can be manufactured quickly and efficiently.
No detail is too large, or too small, to be optimised. This page details some of the steps we take to produce our equipment.
By manufacturing our products in batches we can reduce the total cost.
The Cross Bars (0.5m) are laser cut from Aluminum Alloy sheets and folded before the Aluminum Alloy undergoes a hardening process to increase its strength. Using Aluminum sheets gives us more control over the thickness (and weight) and access to a greater range of alloy compositions, allowing us to produce stronger and lighter parts and equipment.
Our frames are made from lightweight Aluminium alloy tube. By ordering long lengths and manufacturing in quantity using a fully automatic computer controlled tube manipulator and cutter the cost per frame is minimised while maintaining the quality.
The TAR-3 probes have a shape designed by us and are manufactured from 8mm diameter stainless steel. The small diameter increases the insertion pressure making it easer to place the probes into the ground. The taper provides the required contact between the ground and the probe and the slight 'sharpening' at the end provides a sturdy end that is resistant to blunting and damage when the probes hit a hard surface.
Making the probes from 8mm stainless steel allows us to use standard nuts and washers. All of the nuts, washers, set screws are made locally in 'A2' stainless steel. By avoiding the use of custom fittings to hold the probes in place we have reduced weight. The low weight of the TAR-3 Resistance Meter is appreciated by users at the end of the day – during a typical day the probes may be inserted over three thousand times.
By designing our own power supply and dedicated battery charger we are able to use modern Lithium batteries. Our products are fitted with Lithium Ion or Lithium Polymer batteries with a capacity of between 5Wh to 50Wh. By closely matching the battery capacity to usage requirment we can maximise the running time and minimise the charging time and weight.
Lithium batteries are up to 20% more efficient than Nickel-Metal hydride or Nickel-Cadmium batteries when being charged which results in a faster charging time for the same power supply.
For long life and reliability our products use real buttons that give a reassuring feedback. We do not use membrane key pads. Our philosophy is 'Real keys for real people' We use 3M adhesives and polymers which are designed for prolonged and continuous outdoor use.
Our magnetic gradiometer products, the DFG-1 Magnetic Gradiometer and RM Pro Cart system, use Nylon set screws and nuts to maintain their low magnetic signature. To complement these products we manufacture and supply Nylon spanners. You can keep them in your pocket without affecting your results – one thing less to worry about.
Using industry standard USB (5V, 1A) chargers allows users to use any charge to charge the TAR-3 Resistance Meter. You can also use them to charge your mobile phone (or use a mobile phone charger to charge your TAR-3 Meter). The TAR-3 unit can also be charged from a 'Power Bank Charger'. We supply 240V UK Plugs to the UK and 110/230V, 50/60Hz power supplies with world wide adaptor plugs to Europe and the rest of the world.
TAR-3 Resistance Meters can be charged using the 12V Car Adaptor supplied.
Your data is safely stored on a 8GB SD Card. All our products use the same SD Cards and come with an adaptor and USB reader. SD Cards are future proofed. You do not need cables, adaptors, RS232 Ports or USB to RS232 adaptors.
The TAR-3 Resistance Meter has been designed to use standard, readily available, cables (Twin 0.5mm2 240V flexible cord). Replacement cables are available online and from most 'DIY' stores. The 4mm gold plated banana plugs can be removed and soldered on to the new cable using a 25W soldering iron. No specialist equipment or solder is required. Cables are supplied on 50m winders, 100m lengths are an option. Longer lengths, up to 500m, are available subject to a short lead time. Please contact us for details. By using modern components we can make lighter
We focus on every part of our product – large and small. The small include the components used on our printed circuit boards. The resistor in the photograph above is shown next to the point of a pin. (This is not the smallest component we use.) The data sheet for even these components can be seventeen pages long. Before selecting a component we read all of the data sheet and only use components that meet our exacting requirements. The resistor in the picture is a Metal glaze on ceramic, ‘0603’, 1%, 75V. 100ppm/K, Pb free resistor meeting the requirements of AEC-Q200 for automotive use.
Our products include the latest generation of components like the semiconductor chip above. Small, consuming µA of battery power it contains an analogue to digital converter (ADC), a digital to analogue converter, and a Bluetooth™ transceiver capable of supporting Bluetooth 5.1 core features while consuming 3mA (3.3V) of power while transmitting data. By using modern components we can make lighter equipment with longer battery life.
Using small components like the chip above requires specialist solder paste; precise ‘pick and place’ machines, ‘vapour phase’ soldering equipment, and X-ray inspection equipment. By having our PCBs manufactured locally we have access to the latest equipment operated by experienced technicians.
© RM Frobisher (1986) Ltd. 2020