The VELA (Versatile Laboratory Aid and later renamed to Versatile Laboratory Instrument) is a data logging tool that was produced by Data Harvest/Educational Electronics and Leeds University that can be used as a stand alone data logger or connected to a BBC Microcomputer or other suitable computer to allow the downloading of data for analysis.
The VELA was intended to be used in schools and University laboratories to assist in physics and chemistry experiments and with a little imagination it can be used for all sorts of useful data logging applications.
I personally used the VELA whilst at school studying for my A-Levels and made use of its facilities in my Chemistry projects to measure the pH levels of acids and alkali's with unknown molarities in an effort to determine their respective molarity which you can read about on my Beeb in Education page. I also used the VELA to perform additional measurements of a school friends experiment to measure the pH levels of liquids during the fermentation process whilst his primary experiment was to measure the amount of CO2 being produced in the same process.
I've also seen mention of the use of VELA to measure and analyse speech patterns and it is claimed that the VELA data logger was instrumental in the development of "Speech!" by David Hoskins which was released by Superior Software (now Superior Interactive) although I've not been able to corroborate that information.
The VELA has 4 channels of input which are selectable as +/-250mV, +/-2.5V or +/-25V ranges. Each channel can be used independently and one of the built in programs is a four channel digital volt meter. The VELA also has a set of inputs to measure pulses and these pulses can be used to trigger the start and end point of a data logging sequence and much more.
The programming interface was through the keypad which allowed for program selection and time limit configuration amongst other things including configuring the VELA to output its data to the BBC Micro. The VELA is even fully programmable using the numeric keypad and 6802 assembly language programs can be entered into the VELA's 4Kb memory using the decimal numeric representations of the 6802 instruction set.
Once the selected data logging program has been run and the data is stored in the VELA, it can be output via an analogue out to an oscilloscope or digital out to a microcomputer. The digital out connector is driven by a Motorola 6821 PIA and has two banks of data and control lines as well as an auxiliary 5V power feed.
The connection used to connect to the the VELA to a BBC Micro requires a 26-pin to 20-pin cable conversion and uses the VELA's CA0-1 control lines and PB0-7 data lines to connect to the BBC Micro's User Port.
The VELA was in many circles looked upon as difficult to use1,2,3,4 and it's probably fair to say it wasn't the most intuitive of devices to use but with a little patience and study, it could be used to great effect. So much so that I know of people that still use the VELA today. It is through some of these people that I have managed to accumulate some scans of the documentation and dumps of the ROM's for certain models of the VELA that I've made available for download here.
Personally, I always found the VELA to be reasonably straightforward to use and even when re-discovering the VELA after a 19-year gap and initially lacking any manuals, it was relatively straightforward to get up and running.
As part of the Beeb@30 celebrations on the 25th of March 2012, this VELA was on display with my Issue 4 BBC Micro as part of the BBC Micro in Education display. I created several experiments for the day which included a capacitor charge and discharge circuit and an experiment to determine the velocity of an object in free-fall.
In 1992, after a successful A-Level Chemistry project using the BBC Micro and a VELA data logging device, I was commissioned by my teachers to write a simple "Getting Started Guide to VELA" as the original documentation was heavy going and the VELA device was relatively difficult to configure correctly.
Over the years, I have lost (misplaced) my digital copy of the original guide but I do have an original print out of it. I've faithfully OCR'd the original and made some corrections to it making it clearer and easier to read.
Whether it is of use to anyone or not, I don't know but if anyone has a VELA device and needs to figure out how it works, hopefully, my getting started guide should help.