A-level electronics project

[james heads]

hi,

i have to make an electronics project and i was tinking about making
some extra addons for rc cars (nitro mainly). i was hoping that some
of you would be able to give me some ideas on how to get these things
to work and any other ideas i could add in.

anyway here we go.


so far i have the following-

Fuel level detector-
inputs - sensor in tank
Processes - When fuel is low displays a warning
outputs - warning L.E.D.

Battery tester-
Inputs - Circuit testing voltages attached to batteries
Processes - Once batteries fall to a low point Warning L.E.D. is
displayed then later engine is cut out
Outputs - Warning light and engine is cut

Lights-
inputs - L.D.R
Processes - Measures light levels and switches on lights when needed
Outputs - Set of headlights

indicators-
inputs - sensors on servo
processes - voltage going to the servo is tested and depending what it
is the indicators are switched on
outputs - left and right indicators.

speedo-
inputs - sensors on wheels
processes - counts the number of times that the wheel turns and either
stores speed on chip of dispays in 7-segment display.
output - chip with data saved on it or top speed displayed on
7-segment display


as you can see i havent got all that much.

i would Appreciate any ideas that you have on either modifying the
above, circuit diagrams and any other extra ideas you may have.
thx.

[Bubba]

On 27 Jan 2003 11:14:35 -0800, headsy2001@yahoo.co.uk (james heads)
wrote:

>Fuel level detector-
>inputs - sensor in tank
>Processes - When fuel is low displays a warning
>outputs - warning L.E.D.

Pretty simple. An IR LED, an IR phototransistor, 1 or 2 transistors,
3-4 resistors, a very bright LED in a large package, and a lithium
battery holder.

>Battery tester-
>Inputs - Circuit testing voltages attached to batteries
>Processes - Once batteries fall to a low point Warning L.E.D. is
>displayed then later engine is cut out
>Outputs - Warning light and engine is cut

Not simple. Checking the voltage of the battery and lighting the LED
isn't too tough, but driving the throttle servo to idle isn't an easy
thing without a microcontroller.

>Lights-
>inputs - L.D.R
>Processes - Measures light levels and switches on lights when needed
>Outputs - Set of headlights

Very easy. Phototransistor, transistor, a couple of resistors, and
some ultra high intensity LEDs for the lights. Adding brake lights
wouldn't be too tough, either.

>indicators-
>inputs - sensors on servo
>processes - voltage going to the servo is tested and depending what it
>is the indicators are switched on
>outputs - left and right indicators.

Not easy. Servos aren't driven with a changing voltage, it's a pulse
width. There are schematics out there for switches that could be
connected to channel 1 with y harnesses that would do it, though.

>speedo-
>inputs - sensors on wheels
>processes - counts the number of times that the wheel turns and either
>stores speed on chip of dispays in 7-segment display.
>output - chip with data saved on it or top speed displayed on
>7-segment display

I'd put a magnet on the spur gear, clutch bell, or something else
before any differentials and detect it with a Hall Effect sensor.
National Semiconductor makes a few 7 segment drivers, but you'd likely
have to use a microcontroller to do the math and control the output to
the 7 segment drivers.

I think I'd go with the fuel gauge, myself. It would take some
fiddling to get the phototransistor set up just right, but a PCB mount
potentiometer could be used to trim it. Just fill the tank past the
sensors and turn the pot down until the light goes off, then tilt the
car until the sensors are uncovered and see if the light comes back
on. Not much to it. I built the same circuit, with a different output
(agitating hopper for a paintgun), years ago. Took 1 IR pair, 3
resistors, 2 transistors, and an old S148 servo with the stop ground
off the output gear so it would spin and the PCB removed. The entire
circuit was just freeformed without a board and fit into the servo
case easily. For a gas gauge I would wire it all up and seal it in
heat shrink. Just leave the output LED on the board and heat shrink
the whole thing. Mount it someplace where it can be seen through the
window.

Bubba
HPI Micro RS4 Viper GTSR- Absolutely not for sale
AE RC10LSS Diablo VT- Maybe for sale
HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)

[sanj.varah]

I would go for the speedo!

or stick a gyro on the car and make air suspension. its a challenge! i'm
sure the exam boards especially will be impressed. unless they are edexel
and lose the papers

sanj

--
Visit my RC Homepage
http://www.schumacher.clara.net


"james heads" <headsy2001@yahoo.co.uk> wrote in message
news:76690a6f.0301271114.1361fc24@posting.google.c om...
> hi,
>
> i have to make an electronics project and i was tinking about making
> some extra addons for rc cars (nitro mainly). i was hoping that some
> of you would be able to give me some ideas on how to get these things
> to work and any other ideas i could add in.
>
> anyway here we go.
>
>
> so far i have the following-
>
> Fuel level detector-
> inputs - sensor in tank
> Processes - When fuel is low displays a warning
> outputs - warning L.E.D.
>
> Battery tester-
> Inputs - Circuit testing voltages attached to batteries
> Processes - Once batteries fall to a low point Warning L.E.D. is
> displayed then later engine is cut out
> Outputs - Warning light and engine is cut
>
> Lights-
> inputs - L.D.R
> Processes - Measures light levels and switches on lights when needed
> Outputs - Set of headlights
>
> indicators-
> inputs - sensors on servo
> processes - voltage going to the servo is tested and depending what it
> is the indicators are switched on
> outputs - left and right indicators.
>
> speedo-
> inputs - sensors on wheels
> processes - counts the number of times that the wheel turns and either
> stores speed on chip of dispays in 7-segment display.
> output - chip with data saved on it or top speed displayed on
> 7-segment display
>
>
> as you can see i havent got all that much.
>
> i would Appreciate any ideas that you have on either modifying the
> above, circuit diagrams and any other extra ideas you may have.
> thx.

[Alec]

you said it wouldn't be easy to add brake lights so how exactly would you do
this & the gas gague would really be a good idea for long mains. So how
exactly would you construst them both. cool.


"sanj.varah" <sanj.varah@rolls-royce.com> wrote in message
news:1043699304.70501.0@despina.uk.clara.net...
> I would go for the speedo!
>
> or stick a gyro on the car and make air suspension. its a challenge! i'm
> sure the exam boards especially will be impressed. unless they are edexel
> and lose the papers
>
> sanj
>
> --
> Visit my RC Homepage
> http://www.schumacher.clara.net
>
>
> "james heads" <headsy2001@yahoo.co.uk> wrote in message
> news:76690a6f.0301271114.1361fc24@posting.google.c om...
> > hi,
> >
> > i have to make an electronics project and i was tinking about making
> > some extra addons for rc cars (nitro mainly). i was hoping that some
> > of you would be able to give me some ideas on how to get these things
> > to work and any other ideas i could add in.
> >
> > anyway here we go.
> >
> >
> > so far i have the following-
> >
> > Fuel level detector-
> > inputs - sensor in tank
> > Processes - When fuel is low displays a warning
> > outputs - warning L.E.D.
> >
> > Battery tester-
> > Inputs - Circuit testing voltages attached to batteries
> > Processes - Once batteries fall to a low point Warning L.E.D. is
> > displayed then later engine is cut out
> > Outputs - Warning light and engine is cut
> >
> > Lights-
> > inputs - L.D.R
> > Processes - Measures light levels and switches on lights when needed
> > Outputs - Set of headlights
> >
> > indicators-
> > inputs - sensors on servo
> > processes - voltage going to the servo is tested and depending what it
> > is the indicators are switched on
> > outputs - left and right indicators.
> >
> > speedo-
> > inputs - sensors on wheels
> > processes - counts the number of times that the wheel turns and either
> > stores speed on chip of dispays in 7-segment display.
> > output - chip with data saved on it or top speed displayed on
> > 7-segment display
> >
> >
> > as you can see i havent got all that much.
> >
> > i would Appreciate any ideas that you have on either modifying the
> > above, circuit diagrams and any other extra ideas you may have.
> > thx.
>
>

[Bubba]

On Mon, 27 Jan 2003 22:07:00 -0800, "Alec"
<smartalec87@mindspring.com> wrote:

>you said it wouldn't be easy to add brake lights so how exactly would you do
>this & the gas gague would really be a good idea for long mains. So how
>exactly would you construst them both. cool.

The brake lights might not be too tough after I thought about it a
bit. I was thinking that it would be best to y it into the throttle
channel, but then I realized that a circuit could be built that would
turn off the brake lights when the motor was getting voltage. Just
hook it to the motor wires. Then I remembered that you were talking
about a nitro vehicle, not electric, so it's a piece of cake. Just put
a microswitch somewhere in the brake linkage. No real circuitry
involved, just a small battery, a microswitch, and a couple of LEDs
with resistors. Unfortunately I can't be of much help with the gas
gauge circuit. It's been too long since I worked with any electronics
and I can't remember all the details of the circuit. However, I
designed it by flipping through one of the cheap electronics books at
Radio Shack.

Bubba
HPI Micro RS4 Viper GTSR- Absolutely not for sale
AE RC10LSS Diablo VT- Maybe for sale
HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)

[james heads]

wow thx for all the help guys.

any of you got any info on how the servos work because i was just
under the impression there was a positive and a negitive voltage ran
through them.

also i was thinking of doing all of the things i mentioned above
because our couse does not specify that you need any box mode for it
just a working curcuit.

if you find any curcuit diagrams that i can try out then plz either
post them here or e-mail me them at headsy2001@yahoo.co.uk. thx

[Bubba]

On 28 Jan 2003 09:10:22 -0800, headsy2001@yahoo.co.uk (james heads)
wrote:

>wow thx for all the help guys.

No problem.

>any of you got any info on how the servos work because i was just
>under the impression there was a positive and a negitive voltage ran
>through them.

There's a ground and a positive (same voltage as the receiver battery
or whatever is coming from the BEC in the speed control), but they
just power the servo. The signal is the 3rd wire, and it's a pulse
width signal. Basically it's the same pulse width that the transmitter
sends, but demultiplexed and sent to the individual channels. All of
this is coming from old memory, but I think 250 ms is neutral and more
and less are towards the stops. I think the servo sits at one position
until it gets a new position, but I'm not positive on that. I do know
the old radios would pulse the "servo", which was vastly different,
instead of holding the position.

>also i was thinking of doing all of the things i mentioned above
>because our couse does not specify that you need any box mode for it
>just a working curcuit.

Unless the gizmo is going in a very harsh environment I just heat
shrink the board and velcro it down somewhere. Hell, I usually strip
the case off the receiver and heat shrink that, too. Smaller and
lighter that way.

Bubba
HPI Micro RS4 Viper GTSR- Absolutely not for sale
AE RC10LSS Diablo VT- Maybe for sale
HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)

[Tempestnightmare]

If ya want a light kit...just go to www.rcneon.com it is about $35 bucks for
high intensity head light and 2 level tail/brake light...everything it is
the kit..
Jon

"Bubba" <bubba@beer.com> wrote in message
news:3e3623b1.217281349@news.dallas.sbcglobal.net. ..
> On Mon, 27 Jan 2003 22:07:00 -0800, "Alec"
> <smartalec87@mindspring.com> wrote:
>
> >you said it wouldn't be easy to add brake lights so how exactly would you
do
> >this & the gas gague would really be a good idea for long mains. So how
> >exactly would you construst them both. cool.
>
> The brake lights might not be too tough after I thought about it a
> bit. I was thinking that it would be best to y it into the throttle
> channel, but then I realized that a circuit could be built that would
> turn off the brake lights when the motor was getting voltage. Just
> hook it to the motor wires. Then I remembered that you were talking
> about a nitro vehicle, not electric, so it's a piece of cake. Just put
> a microswitch somewhere in the brake linkage. No real circuitry
> involved, just a small battery, a microswitch, and a couple of LEDs
> with resistors. Unfortunately I can't be of much help with the gas
> gauge circuit. It's been too long since I worked with any electronics
> and I can't remember all the details of the circuit. However, I
> designed it by flipping through one of the cheap electronics books at
> Radio Shack.
>
> Bubba
> HPI Micro RS4 Viper GTSR- Absolutely not for sale
> AE RC10LSS Diablo VT- Maybe for sale
> HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)

[Alec]

you said a micro switch do you mean a little toggle to turn it on and off or
is there a way to make it intensify when you brake i know you can buy these
kits but constructing one would be a cool challeng.
so if you can help thanx in terms of what kind of micro switch.


"Tempestnightmare" <tempestnightmare@comcast.net> wrote in message
news:iSWdnXKYHMJNoqqjXTWcpw@comcast.com...
> If ya want a light kit...just go to www.rcneon.com it is about $35 bucks
for
> high intensity head light and 2 level tail/brake light...everything it is
> the kit..
> Jon
>
> "Bubba" <bubba@beer.com> wrote in message
> news:3e3623b1.217281349@news.dallas.sbcglobal.net. ..
> > On Mon, 27 Jan 2003 22:07:00 -0800, "Alec"
> > <smartalec87@mindspring.com> wrote:
> >
> > >you said it wouldn't be easy to add brake lights so how exactly would
you
> do
> > >this & the gas gague would really be a good idea for long mains. So how
> > >exactly would you construst them both. cool.
> >
> > The brake lights might not be too tough after I thought about it a
> > bit. I was thinking that it would be best to y it into the throttle
> > channel, but then I realized that a circuit could be built that would
> > turn off the brake lights when the motor was getting voltage. Just
> > hook it to the motor wires. Then I remembered that you were talking
> > about a nitro vehicle, not electric, so it's a piece of cake. Just put
> > a microswitch somewhere in the brake linkage. No real circuitry
> > involved, just a small battery, a microswitch, and a couple of LEDs
> > with resistors. Unfortunately I can't be of much help with the gas
> > gauge circuit. It's been too long since I worked with any electronics
> > and I can't remember all the details of the circuit. However, I
> > designed it by flipping through one of the cheap electronics books at
> > Radio Shack.
> >
> > Bubba
> > HPI Micro RS4 Viper GTSR- Absolutely not for sale
> > AE RC10LSS Diablo VT- Maybe for sale
> > HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)
>
>

[Alec]

oh yeah you guys seem to know a lot about electronics so i have a question
how do you make a little motor work like a sevo. As in tems of limiting how
far it will rotate. And then go back. i have asked electronic newsgroups but
they can't seem to help any info. please.

Thanx
"Alec" <smartalec87@mindspring.com> wrote in message
news:b17icv$aqs$1@slb5.atl.mindspring.net...
> you said a micro switch do you mean a little toggle to turn it on and off
or
> is there a way to make it intensify when you brake i know you can buy
these
> kits but constructing one would be a cool challeng.
> so if you can help thanx in terms of what kind of micro switch.
>
>
> "Tempestnightmare" <tempestnightmare@comcast.net> wrote in message
> news:iSWdnXKYHMJNoqqjXTWcpw@comcast.com...
> > If ya want a light kit...just go to www.rcneon.com it is about $35 bucks
> for
> > high intensity head light and 2 level tail/brake light...everything it
is
> > the kit..
> > Jon
> >
> > "Bubba" <bubba@beer.com> wrote in message
> > news:3e3623b1.217281349@news.dallas.sbcglobal.net. ..
> > > On Mon, 27 Jan 2003 22:07:00 -0800, "Alec"
> > > <smartalec87@mindspring.com> wrote:
> > >
> > > >you said it wouldn't be easy to add brake lights so how exactly would
> you
> > do
> > > >this & the gas gague would really be a good idea for long mains. So
how
> > > >exactly would you construst them both. cool.
> > >
> > > The brake lights might not be too tough after I thought about it a
> > > bit. I was thinking that it would be best to y it into the throttle
> > > channel, but then I realized that a circuit could be built that would
> > > turn off the brake lights when the motor was getting voltage. Just
> > > hook it to the motor wires. Then I remembered that you were talking
> > > about a nitro vehicle, not electric, so it's a piece of cake. Just put
> > > a microswitch somewhere in the brake linkage. No real circuitry
> > > involved, just a small battery, a microswitch, and a couple of LEDs
> > > with resistors. Unfortunately I can't be of much help with the gas
> > > gauge circuit. It's been too long since I worked with any electronics
> > > and I can't remember all the details of the circuit. However, I
> > > designed it by flipping through one of the cheap electronics books at
> > > Radio Shack.
> > >
> > > Bubba
> > > HPI Micro RS4 Viper GTSR- Absolutely not for sale
> > > AE RC10LSS Diablo VT- Maybe for sale
> > > HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)
> >
> >
>
>

[Bubba]

On Tue, 28 Jan 2003 21:44:04 -0500, "Tempestnightmare"
<tempestnightmare@comcast.net> wrote:

>If ya want a light kit...just go to www.rcneon.com it is about $35 bucks for
>high intensity head light and 2 level tail/brake light...everything it is
>the kit..

Unfortunately their kit needs a brake light output on the ESC and
neither of my ESCs or the one I plan on picking up shortly has that
output. Besides, $35 is enough to put lights in every body I own ;)

Bubba
HPI Micro RS4 Viper GTSR- Absolutely not for sale
AE RC10LSS Diablo VT- Maybe for sale
HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)

[Bubba]

On Tue, 28 Jan 2003 19:38:55 -0800, "Alec"
<smartalec87@mindspring.com> wrote:

>you said a micro switch do you mean a little toggle to turn it on and off or
>is there a way to make it intensify when you brake i know you can buy these
>kits but constructing one would be a cool challeng.
>so if you can help thanx in terms of what kind of micro switch.

This is a microswitch:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F010%5F007%5F005%5F000&product%5Fid=275%2D017

Basically just stick it on the servo so the servo arm hits it when you
hit the brakes and wire it to the brake lights. Piece of cake.

Bubba
HPI Micro RS4 Viper GTSR- Absolutely not for sale
AE RC10LSS Diablo VT- Maybe for sale
HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)

[Bubba]

On Tue, 28 Jan 2003 19:44:35 -0800, "Alec"
<smartalec87@mindspring.com> wrote:

>oh yeah you guys seem to know a lot about electronics so i have a question
>how do you make a little motor work like a sevo. As in tems of limiting how
>far it will rotate. And then go back. i have asked electronic newsgroups but
>they can't seem to help any info. please.

Not easy at all. You'd have to have a way to get feedback from the
motor (servos use a potentiometer) and something to tell the motor
when to turn which way. Stepper motors would work, but would also need
driver electronics.

Bubba
HPI Micro RS4 Viper GTSR- Absolutely not for sale
AE RC10LSS Diablo VT- Maybe for sale
HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)

[james heads]

o.k.
i think i am gonna be o.k. making the electronic throttle controler,
fuel indicator, lights and indicators. the only problem that i can see
now is the speedo. thats gonna take a very long time.
unless i rip the one off my bike =)

[Alec]

i am only aware of using a pot. for a volume control so how can you make it
stop and read the motor.

Thanx
"james heads" <headsy2001@yahoo.co.uk> wrote in message
news:76690a6f.0301290701.7adc92b3@posting.google.c om...
> o.k.
> i think i am gonna be o.k. making the electronic throttle controler,
> fuel indicator, lights and indicators. the only problem that i can see
> now is the speedo. thats gonna take a very long time.
> unless i rip the one off my bike =)

[Bubba]

On Wed, 29 Jan 2003 18:41:52 -0800, "Alec"
<smartalec87@mindspring.com> wrote:

>i am only aware of using a pot. for a volume control so how can you make it
>stop and read the motor.

The pot moves with the output shaft of the gearbox (at least in the
case of most RC servos) and gives the board in the servo position
feedback which it turns into a pulsewidth. Basically the servo board
moves the servo until the feedback pulse and input pulse from the
receiver match.

Bubba
HPI Micro RS4 Viper GTSR- Absolutely not for sale
AE RC10LSS Diablo VT- Maybe for sale
HPI RS4 Sport 2- Wanted, cheap and unbuilt ;)