tks
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| posted on 14/1/06 at 08:04 PM |
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sparking power
whats the voltage needed for a sparkplug to ignit 12cc of fuel??
200.000volts???
how the bloody hell could 1 gallon go with 5volts..and 0,005Amps...
its impossible.. and if you connect a small cap 1uf even less possible..
and i bet that the sparking bit of the sender is always in the fuel...
Tks
The above comments are always meant to be from the above persons perspective.
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RazMan
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| posted on 14/1/06 at 08:07 PM |
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Try reversing the polarity of a small tantulum capacitor - they give such a BANG they are used as detonators in some parts of the world
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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tks
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| posted on 14/1/06 at 08:10 PM |
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yeah
but int he circuit they are fare away of the fuel, sow
no fuel bang just an cap bang...
connect an microchip 24LCXX to 13volts..
it will explode..sow wear glasses...
Tks
The above comments are always meant to be from the above persons perspective.
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MikeRJ
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| posted on 15/1/06 at 03:05 PM |
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One thing no-one has mentioned is that many older cars (definately Escort, not sure about Sierra) used a mechanical voltage regulator to provide a
stabilised voltage for the water temperature and fuel guages.
If this is the case, then the mechanical regulator is absolutely no good whatsoever for an electronic gauge, and would need to be replaced with a
solid state equivalent, using e.g. a 3 terminal regulator.
The old LM3914 is a nice and easy, purely analog way of converting a voltage to a dot or bar display. A PIC could also do the job for very little
more money (LM3914's are not overly cheap), with the advantage that the level sender could be linearised to account for odd shaped fuel tanks
etc.
If a dot/bar coolant temperature display is required, the PIC solution looks even more tempting. This would take 2xLM3914's (or at least a lot
of extra components to muliplex one of them) but a single PIC could drive two LED displays by multiplexing with only a little extra firmware effort
and a few extra components. A PIC may also be handy to linearise the (highly non-linear) thermistor which is used in coolant temperature sensors.
In the case of using a PIC, the voltage reference for the sensors may be derived from the 5volt regulator used to power the PIC, which would give more
than adequate accuracy and tempco for this application (orders of magnitude better than the old mechanical ones).
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MikeR
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| posted on 15/1/06 at 05:44 PM |
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Ok, how much can a PIC do??
I want oil pressure, oil temp, water temp, fuel.
what would i need to drive 4 lots of leds?
Running what, 1 sample a second for fuel, water, oil temp and 5 or 10 samples for oil pressure.
I can code c (and did machine code [cough] years ago). I can't do hardware.
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k33ts
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| posted on 16/1/06 at 08:18 PM |
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poppe or tks have either you had time to knock up a drawing yet for this circut
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MikeRJ
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| posted on 16/1/06 at 11:14 PM |
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quote:
Originally posted by MikeR
Ok, how much can a PIC do??
I want oil pressure, oil temp, water temp, fuel.
what would i need to drive 4 lots of leds?
Running what, 1 sample a second for fuel, water, oil temp and 5 or 10 samples for oil pressure.
I can code c (and did machine code [cough] years ago). I can't do hardware.
Even one of the smaller PIC's could do this with ease. You need 10 pins to drive the LED's, 4 pins to control the multiplexing
transistors, 4 analog inputs, power and ground making 20 pins. There are a few 20 pin devices, but one of the 28 pin PICs would be a better fit,
giving room for any extras you think of.
Obvioulsy you will need some signal conditioning and protection on the analog inputs to clamp spikes and do some high frequency filtering, the rest of
the filtering can be done by the PIC.
What you really need to know are the resistance characteristics of the sensors. The temperature sensors will all be thermistors, with usualy a
resisatnce of around 2500Ohms at 25degree C, but I don't know much about the pressure sensors. The fuel level sender will have a maximum
resistance in the order of 100 Ohms.
If you are serious about this I'd be happy to lend a hand with the design and firmware.
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MikeR
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| posted on 16/1/06 at 11:47 PM |
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To be honest I'm getting very serious!
I've been after a fuel gauge for a couple of years (its a slow build) and i've put off buying gauges a few times.
I've found some i like but the seller is in hong kong and won't answer my questions.
This way i get to do something that is cheapish, lightweight, and hopefully works well.
Programming shouldn't be an issue and i'm actually looking forward to it.
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NS Dev
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| posted on 17/1/06 at 12:32 AM |
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Oh Mike!!
I'll be towing your 7 on the back of mine yet!!
(Even if I do have to ring when I run out of fuel!!)
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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MikeR
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| posted on 17/1/06 at 12:39 AM |
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oi, i've got a sneaky suspicion you'll be after one of these dash units .........
cheap, lightweight ......... hmmm, suppose that means my car (when complete) will STILL weigh less than yours and STILL get over the speed bumps :p
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NS Dev
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| posted on 17/1/06 at 08:32 AM |
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weigh less than mine!!!!
lol Pah!!
I might have the XE engine but it doesn't weigh that much more than a crossflow and I don't have a cast iron bellhousing or a steel floor
or steel shocks or heavy cortina calipers....................................!
on a serious note, I would prob be interested in a "does it all" dash pod.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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MikeR
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| posted on 17/1/06 at 12:54 PM |
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tough - not making you one till you say sorry :p
And remember, calipers can be changed, bell housings can be changed - the floor only weighs the same as 3mm ali (which road going cars should have for
penetration protection).....
and my engine can be bored out to make it lighter ............... wonder how much lighter 250cc's extra capacity would be ????? 
[Edited on 17/1/06 by MikeR]
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NS Dev
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| posted on 17/1/06 at 01:11 PM |
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Who says road cars need 3mm ally floors!!?????
1.6mm (or was it 1.2mm??) on mine!!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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MikeR
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| posted on 17/1/06 at 05:45 PM |
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me - based on the penetration characteristics of ali!
(ahem, i think we're doing a thread hijack!)
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k33ts
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| posted on 19/1/06 at 08:30 PM |
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quote:
Originally posted by k33ts
took some measurements of current fuel sender one of etb instruments items £16ish
float at bottum tank empty 260 ohms
float at top tank full 35 ohms
which equates to voltage measurements at sender with fuel gauge connected.
3.492v empty
3.320v 1/4
2.973v 1/2
2.399v 3/4
1.663v full
although i dont know how to doit i cant see it that hard to trigger say 5 leds from this
if some one can design it i'll be the gineau pig as iknow a lot of people wuold be interested and could use an idea like this
is anyone prepared to have a crack at this for beer tokens?
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Bob C
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| posted on 20/1/06 at 12:33 AM |
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All you chaps who want LED bargraph displays should buy one of mine........
http://freespace.virgin.net/bob.carter/files/dashbunf.pdf
Actually one has been SVA'd successfully.
Limited edition only . . . .
200 notes gets most of the stuff you need -
Cheers me dears
Bob
PS are you all fed up with me trying to flog my spare PCBs yet.... sorry
 
Rescued attachment bensstuff.jpg
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k33ts
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| posted on 20/1/06 at 12:58 AM |
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looks smart mate but i only wana do the fuel!!
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MikeR
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| posted on 21/1/06 at 05:21 PM |
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Bob, would you be prepared to look at doing a cut down version ??????
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Bob C
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| posted on 21/1/06 at 10:50 PM |
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Hah - no - I did a dash for me & it effectively costs the same to get 10 PCBs as one so I thought I'd flog the spares - make the enterprise
a bit more worthwhile. It's not like I'm trying to make a living or even a profit with them. They've not proved as popular as I
thought they would, though I've sold a couple. But, as I say, I don't intend to sink any morre time into that part of the endeavor!
Cheers
Bob
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tks
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| posted on 22/1/06 at 04:23 PM |
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mhh
The trick is...
that that voltage is the input for some device..(like i early mentioned to an pic)
from that input the pic knows...how much leds it needs to enable...
there are already several examples shown here up i would advise just buy one you like and start spoofing the guy who posted with the questions to have
it worked...
the only problem i see in the LM circuit is dat if you take a bumb and the fuel will move..then your leds will go crazy!!
And in the pic we could make software to
catch fuel level changes who are more than the maximum MPG that the car makes...
Also the pic could measure every 10min instead of (the biggest number you can think of per second)
Tks you even can build it with memory sow that if you park at a hill the sensors knows that it doesn't need to reset the counter.
Our corsa for example when i park at work
gives allot more fuel than it has (like 10Liters)..
sow after 3min you see the right level of fuel in it..
Tks
The above comments are always meant to be from the above persons perspective.
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MikeR
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| posted on 22/1/06 at 04:26 PM |
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(silly mode)
why not have a level sensor for in the car, so that the pic can calc that if its at 10% nose up the sensor will read 15% too little ?????
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tks
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| posted on 23/1/06 at 07:34 PM |
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MIKER
if you like flashing leds then just do it with the circuit...
and just when you want to know the fuel level it will be flashing....
while you are breaking for example..
An pic depending on its size can do everything!
If you want more things to show i wouldn't bother with leds, buy from ebay for example an 2x16 LCD display with black light..
i brought 5 from japan the other day..work nicely..(with blue backlight)
Combine that with 2 buttons...
and you can shift menu's , reset things...
or without the buttons but an timer...
(like an slide show)
with pics you control the world.
Tks
The above comments are always meant to be from the above persons perspective.
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andyharding
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| posted on 23/1/06 at 07:45 PM |
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I accidently shorted the battery across the fuel sender once and I'm still here to tell the tail! Guess it has enough resistance not to get hot?
Who knows!
Are you a Mac user or a retard?
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NS Dev
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| posted on 23/1/06 at 08:01 PM |
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quote:
Originally posted by andyharding
I accidently shorted the battery across the fuel sender once and I'm still here to tell the tail! Guess it has enough resistance not to get hot?
Who knows!
The fuel cools it a treat!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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