At long last, I think that I have solved the High Voltage stabilisation problem. I have tried a series of different switched mode power supply chips and have now found one that I am happy with. I decided to meet and exceed the EU spec for this kind of equipment and did my testing switching between loads of zero and 25 mA. Between 0 - 80 volts it stabilises nicely within 20 mV.
Click on the thumbnail and you will see most of the circuit bread-boarded. Bottom right is the twin processor board, with the software running on the LCD. Top right is the HV PSU. Bottom right is the HV driver board. Please note that this design is only for the hospital trials version. The Twin processor board has a DS1370 real time clock for the data logger. It also has one megabyte of flash eprom for logger data storage. What you see is just a 'lash up' for testing.
The final device will have a much simpler processor set-up and no data logger. I have actually made up the processor board for the El Cheapo version. I agonised for quite sometime about indicators for the patient. LCD's have come down in price to below £1, so I have decided to use one rather than LED's etc.. It will be a 16 x 2 line LCD and not the 40 x 2 shown in the photograph, although I think I will use the latter on the trials version .... for bull-shite purposes. I obtained a smart aluminium case for the first one today, but it will not be ready for the Greece trip.
Other ideas for Greece.
I think I have given up on Greece !. However I decided to have a look a a few electronic ideas, small products suitable for EBAY. Holes for ideas come and go on EBAY quite fast. At the moment there may be an opening for a serial to parallel, LCD driver PCB, so I have knocked one up to see what the problems are.
The grey box, yellow block and the cables are only used for programming the micro-processor when writing the program. Normally the standard LCD plugs straight into the yellow PCB. It can operate on any baud rate, true or inverted.
Originally the idea was to produce a product that could fit into an envelope, so that ruled out complete products unless they were very small. Another approach was to only cater for the electronic enthusiast market, in which case the 'product' would be a PCB and a programmed micro-processor. It also means serving a market that is too small to attract attention from the big boys and in particular, the Chinese. So I am having a look at an advanced function generator at the moment. I have two different design PCB's done and populated but not had time to look at the software. I am not 100% sold on the idea of electronic products for the island, but maybe things will become more clear after my visit there.
One of the reasons I wanted the pain suppressor ready for Greece is that I had hoped to get a volunteer to test out the sexual stimulation idea. With the chips I have chosen it will be a simple task to add some circuitry and software to provide this function. If there is any mileage in the application I feel sure that the patient would prefer external stimulation to a dodgy spinal implant operation. I imagine the operation must be quite expensive. Since the original paper I have seen nothing of further developments in that area. I am wondering if it would work for men !.
I must have another look at the direct printing of PCBs as that really does have possibilities. I have had no replies from the Chinese manufacturers yet. That mate ... is it for the moment.
I have read the book you sent ... just in case. For something that was developed over 10,000 years ago it is quite a complex subject. The moulds are straight forward, so if they want me to do anything about the turtles, I guess I can now. I think they would have to buy the slip locally as I cannot imagine how one would get grog there ... except with a big hammer Hi!. I will take some catalogues over there for them, just in case. Adio .....