Voltlog #225 – Taking A Look Inside A Bosch/Audi ECU EDC15VM+

Welcome to a new voltlog, today we’re doing a teardown of an automotive ECU which stands for engine control unit. Every car has one of these, unless it’s very old and doesn’t have electronic control of the engine. This is a small computer that reads a bunch of sensors like air temperature, air pressure, fuel pressure, rpm, crank shaft position, pedal position and various others and then based on these inputs will calculate various parameters and control outputs like the fuel pump, injectors, spark plugs, etc.

I’ve never opened one of these up but we should find something interesting to see in here, at least from the point of view of construction methods because these things need to run smooth even in the hardest conditions like very hot weather or very cold weather as well as endure water pouring right onto them all while withstanding high levels of mechanical shock and vibrations. So it’s likely we will see a nice seal on the enclosure, as well as conformal coating on the inside.

What we find inside might differ a lot depending on the generation of the ECU, older ones having to use more discrete components, while newer ones are integrating a lot of components into a single chip. I’ve worked briefly for Freescale which was building such a newer chip in partnership with BOSCH and it was amazing the level of integration they had: everything from multiple mosfet drivers, differential amplifiers for current sensing with programmable gain, dc-dc boost converter as well as a multi core processor was all integrated on the same chip, as you can imagine this can save quite a bit of money on the final build so that’s the direction things are heading.

The one I have here is from an Audi A6 model C5 which was manufactured between 1997 and 2004, this one is likely made in 2001, judging by a date code I see on the label and it’s from a 2.5 liter TDI engine. I got it from one of these auto dismantling businesses from ebay, I don’t know if it’s ever been opened before, but we will find out soon. 

Voltlog #183 – Building A Resistance Standard With Vishay VHP100 Resistors

Welcome to a new Voltlog, today I’m going to be building a precision reference box, using these precision Vishay resistors, they were sent to me for free by Vishay, these are from the VHP100 series and they are the ducks guts when it comes to resistors. They have incredible stability, across the entire range of -55 up to +125 degrees Celsius they will vary less than 60ppm. So as you can see they had to define the number over the entire temperature range because if they would have done it traditionally per degree C the number would have been essentially 0.

These are built using a special technology called bulk metal foil, wrapped on a ceramic substrate. Then the assembly is suspended in oil and hermetically sealed in this metal can, thus it’s immune to humidity changes. Every one of these resistors is basically custom made so you can order them in any value, but as expected they don’t come cheap. Purchasing these in some standard values carried at the big distributor will cost you around $70 a piece.

Voltlog #180 – Vishay VHP100 Foil Resistors With Zero TCR

If I get this built correctly, with the performance of these resistors, once the box is finished and calibrated it should be good for life. Because I would only be using it in the lab which regarding the temperature varies from 20 to 30 degrees C maximum.

The construction video will follow soon after I receive the aluminium enclosure, until then thank you for watching this and don’t forget to subscribe and hit the small bell icon to be notified of new uploads.