is anyone out there anygood at electronic circutry.
ive been looking at buying new clocks except all the ones i like dont make a fuel gauge.
i was thinking of having a row of leds maybe 8-10 going green to red for fuel instead of a gauge so i can have the gauges i like
could anyone draw me up a circut obviously it will depend on the sender which im geussing would be a case of measuring the impedance from empty to
full
any help would be greatly appreciated.
not much help but do a search its been covered before as i wanted to do this. People get scared - fuel, electrics, creating your own circuit putting
different voltages / amps down it, fuel vapour, bang........
love to have a similar thing tho!
found it cheers, perhaps ill forget that idea then.
did anyone actually try it in the end then?
If they tried and it went bang ........ who will ever know?
how about 1 light coming on when you get down to say 1/4 tank
i know this sounds like a bodge but would this work and be safe
fixing the proper gauge for the sender under the dash and gluing a micro swith to the face so the needle switches it
go on laugh but i need something as im determined not to have s**tty looking clocks
and if dont have anything ill always b running out siv head
[Edited on 12/1/06 by k33ts]
I knew this Degree in Electronic Engineering Im studying would come in use someday.
The Easiest way would probably to use a LM3914 Bargraph Display Driver
If you could get me a wiring diagram for the type of sender your using and also its resistance when its at the top of the swing and the resistance and
the bottom of the swing I could sort you out with circuit diagrams and whatever chips you need to do it, as well as pointing you in the right
direction to components
Little bit busy at the moment with exams, but should be able to sort it no problems.
Lee
the only reason i came up with this bodge idea is because there has already been a discussion on this forum about the safety aspect. ie messing with
electrical circuts going through the petrol tank.
i appreciate your help but to be honest after reading the discussion im to afraid to try it fryed chicken springs to mind.
it would only take a small mistake to make one hell of an explosion
Once you've done the circuit could you pass it to me. As i've said in the other thread, my mate designs fuel systems for a living. I'll
try and persuade him to cast an eye over it - i'm not sure he'll say yes (liabilities etc) but its worth a try.
Might also be worth mentioning how to adjust the circuit so others can use it with different senders.
I'll happily throw a few beer tokens your way if you can sort us out.
Why are voltages being put anywhere near the tank, surely it can be done or resistance or even continuity.
Something like a cheep moisture detector in the side of the tank or hung down from the top at 1/4, 1/2, 3/4 and full levels whould do the trick.
Thats pretty much how detectors called a "watchman" on a heating oil tank work to show the level to the occupants of the house withought
going outside. As the (oil in this case) makes the circuit it confirms its full to that level.
Only trouble is it would prob read funny in the corners unless you set the detector behind a baffle or in a tube.
I last did electronics at GCSE [cough] years ago.
To measure resistance - which is all the fuel sender does you need some current to be passing - ie some volts.
Now in theory this is really easy, its PROBABLY (i've no idea) designed for 12 volts, if we put 3 volts through (or less) and measure resistance
then we should be safer ......... look at it another way, lots of people have been making fuel senders since the 1950's. Can't be that
difficult.
I believe westfield do one - except its not cheap.
quote:
Originally posted by k33ts
how about 1 light coming on when you get down to say 1/4 tank
i know this sounds like a bodge but would this work and be safe
fixing the proper gauge for the sender under the dash and gluing a micro swith to the face so the needle switches it
go on laugh but i need something as im determined not to have s**tty looking clocks
and if dont have anything ill always b running out siv head
[Edited on 12/1/06 by k33ts]
Naah, you'll just have your mobile and call either Chris or me begging we come out with a gallon or two of fuel.
Get some blooming LEDS in - weigh nout compared to that big fat engine and lardy a*se!
quote:
Originally posted by k33ts
the only reason i came up with this bodge idea is because there has already been a discussion on this forum about the safety aspect. ie messing with electrical circuts going through the petrol tank.
i appreciate your help but to be honest after reading the discussion im to afraid to try it fryed chicken springs to mind.
it would only take a small mistake to make one hell of an explosion
quote:
Originally posted by MikeR
Naah, you'll just have your mobile and call either Chris or me begging we come out with a gallon or two of fuel.
Get some blooming LEDS in - weigh nout compared to that big fat engine and lardy a*se!
ive gota measure the resistance with a meter if u could translate that resistance to led's
i know alittle about electronics and to be honest didnt think it would be to much of a problem doing it
ive just taken my gauge apart two resistors going to a wound coil, that looks more scary
surely an electronic circut would be safer anyhow in my eyes anyway
westfields led meter and sender is just over £100
ill measure tmy sender tomorrow
doing searches harley davidson do a retro fit one aswell
ive used one for years but dony know. how does the multi meter measure it?
surely its the same sort of thing that we want to achive
[Edited on 13/1/06 by k33ts]
can somoen put linky to the circuit?
actooally this is an ideal application for a PIC?
or can be done using comparators - how many LEDs to display range?
regarding electric current in your petrol tank; I've been trhouogh all of this, you tend to think about such things when you are sitting on top
of 10 gallons in a land rover!!
it isn't that much of a concern; petrol needs to be in the right properotion mixed with air to be explosive, if it burnt that easily, noone would
ever have starting or running problems!
also being volatile and having a vent, the air would get displaced by petrol putting the mixture into the non explosive tange.
you would design the circuit so that only low currents go trough the sender in case something goes wrong - usaully the fuel guage has high
resistance to limit current.
the trick is an pic
i would go for an
PIC818/819 it has an internal 8Mhz Osciliator sow less components are neded...
then you will need
4 1K resistors
1 7805
1 1uF cap
1 0,1uF cap
1 100uF cap
1 diode
5 leds would be enough??
5 resistors of 250Ohms (for the leds)
2 plane pots (to setup min level) and max level)
We will measure with one adc port the actual value readed.
with 2 others we will tell the pic our maximum and minimum level..of our sender....
its very easy and basic, sow the program
can be made easy and fast..
easy for a couple of pounds... its all done
Tks
Using a PIC is a bit overkill for a fuel guage isnt it?
Just use an LM3914, its a voltage to bargraph display driver! Fully configurable by a few resistors.
Use it to measure the voltage dropped across the sender unit, 1 chip, few resistors and 10 LED's and its done. Also has some nice features on it
too like dot mode or progressive, and a dimmer for the LEDS.
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
I'd like to now re-iterate the bit about volts and restistance. Can't remember who was asking but that perfectly describes the issue - volts
go through the fuel tank.
Ok, its pretty safe to assume this will be ok but if we get it wrong ......
man, did you see that car, it went like a bomb!
Yes its true,
an PIC is overkill but its cheap and its FREE.
Ok, make than the bloody sheme if its sow easy..
Tks
Current flows through the sender, and the voltage is dropped across the resistance!
The circuit I will design will not put any more load on the sender guage, i.e it will be passive!, you can use it in conjunction with an analouge
meter fuel guage or you can replace it with a resistor of the same value, ive got the circuit here, just need to do a few calculations, It can all be
done for under a tenner too, and u can have anything from 1 light to ten lights to show fuel levels.
Lee
Lee - i want your babies.......
(to hold them hostage till you produce the circuit diagram - what did you think i meant?)
It is not uncommon in certain applications in particular cars, to use one sender, and use op amps wired to run as voltage followers measuring the
voltage drop across the sender, then send the output of each opamp to the gauge or daq.
This is not a big deal with any resistive/variable resistance sender, whether it be measuring fuel quantity, temp, or pressure; as long as the end
result is correctly calibrated. You can even amplify +/- to achieve the required range.
Make sure that the voltage supply to the sender is properly regulated, and use large capacitors to cut out RF interference.
The whole lot; opamps, resistors, capacitors, and a piece of perforated copper circuit board would total only £2-£3, from Maplins, RS or Farnell.
Syd.
if you solder your connections properly and use a manufacturers sender, there is no chance of an explosion. At all IMHO.
Ive tried lighting my hob from a 12v spark, it proved impossible, and proper electrics doesnt spark or even get hot. (the resistor might get warm i
suppose...)
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
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
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
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).
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.
poppe or tks have either you had time to knock up a drawing yet for this circut
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.
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.
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!!)
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
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.
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]
Who says road cars need 3mm ally floors!!?????
1.6mm (or was it 1.2mm??) on mine!!!
me - based on the penetration characteristics of ali!
(ahem, i think we're doing a thread hijack!)
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
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
looks smart mate but i only wana do the fuel!!
Bob, would you be prepared to look at doing a cut down version ??????
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
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
(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 ?????
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
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!
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!