Quote:
Originally Posted by arctan
Indeed. I remember starting from having very little resources as kid connecting precious things like transistors together, with very little understanding. Then later being in a company, surrounded by Gurus, with an unlimited radiospares account. And now I'm back to having made a 940 code reader box, but having to take it to a mates workshop because I can't find my soldering iron. If I meet one of the Gurus again, I might ask them how to build a code reader with a numeric display- then I'd be king of the code readers, given the nice designs I've seen on this forum!
On the 555 front, I looked up the current capability, what with it being a small chip. 200ma. I don't know if that will suit your 'tickle the carb'
project? I looked around for 'hi power alternatives to ne555' and frequently saw that people stick a power mosfet on the output. And supporting components etc. And then a bit of lateral thinking gave me the name 'Vellerman kits'.
Velleman Interval Timer Minikit MK111
VellemanMK1115410329001117
ex VAT £3.25
http://www.velleman.co.uk/contents/en-uk/p37_mk111.html
Build it yourself or get the iron out. 3 amp relay. Is 3 amps enough though?
And good luck with the in tank pump. One day I might attend to my fuel gauge sender, which is 'non linear' below 50 pc...
And I very much take your points about swapping the RSR. On something else recently, I can't remember what, the phrase ' if it ain't broke' really finally came home to me.
I might just flash the spare relay on the fan circuit, or even just battery it and measure the contacts.
Maybe I should get off my bum, and clean up the contacts on my sunroof switch, with a spare to hand, in case I break it...
Cheers. |
Similar beginnings then John!
Interesting thoughts about the Vellemann kit, i wasn't sure if they were still in existence with the demise of Maplins as i believe there was some sort of owneship deal between the two of them. That kit you linked to is an astable set up, i need a monostable set up and so far, the favourite set-up seems to be a blocking diode on pin 2 connected to the drivers door pillar switch for the trigger pulse. If this 760 is like the other 740s i've had, the drivers switch will be a two element animal, one for the courtesy lights in general and the other to trigger the courtesy light timer.
The way it is at the moment, there's a connection from the -ve end of the coil on the fuel pump relay to the ECU, when the ECU takes this low, the fuel pump relay is energised. My idea is to interrupt this cable with a SPCO relay, when the coil of said relay is energised, it will take the fuel pump relay coil to earth while disconnecting the ECU from the relay. This will prime the pumps for 2-3 seconds or whatever the time is set at on the 555 circuit, then hand control back to the ECU by de-energising the relay.
The 555 is capable of operating most relays so that shouldn't be a problem. It would have to be set up so the 555 was sourcing the relay, the big problem with the one i bought on fleabay is that it sinks the relay which would obviously draw more current almost all of the time - whether i'm in the car or not.
Interesting idea about adding a numerical readout to the Volvo code reader. As i understand it, each code is 3 digits and there are no codes that have a zero in - is that correct?
If so, the first digit is fairly easy - link the pulse that currently lights the LED on the code reader to the input of a BCD counter, the output of that to a 7-segment driver and a 7-segment display.
The next digit is a bit more awkward and also gives you choices on how to do the rest of the display. First, you need to detect the pause, a missing pulse detector if you like. When this missing pulse is detected, you either need to rest the single 7-segment display/counter so the next pulse starts the count again or moves the pulse input to the next counter/display driver. Likewise with the next digit.
Then you have another choice - if you've got a 3-digit display for the first code, does it reset after the first code and then display the second or does it move on to a second set of digits and if so, where do you stop? Do you have ten 3-digit displays?
There are several ways and means of doing it, cost would probably become a limiting factor though!
