russbost
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| posted on 26/3/18 at 01:17 PM |
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Electronics experts! Simple circuit needed!
One for those of you into electronics rather than specific car electrics.
I need a simple circuit - as simple as possible, which can sample a voltage ranging from 0 - 6v & can switch to provide an earth path at, or
within very close parameters, 3.85V - it mustn't ecognise 3.5V or 4.2V as being the same, so would need an accuracy of around 0.1V, preferably
adjustable for setting up purposes. Source voltage to power the circuit would be normal car electrics, so say 12.5 to 14.5V
Something ready built would be great, but happy to solder a few components together if required
Any ideas?
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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gremlin1234
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| posted on 26/3/18 at 01:40 PM |
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so you seem to want a voltage controlled switch.
strangely the 555 can be used for this:
http://www.circuitdiagramworld.com/led_circuit_diagram/Voltage_Controlled_Switch__NE555__2879.html
(which is a reprint of)
http://www.eeweb.com/blog/extreme_circuits/voltage-controlled-switch-using-555-timer
though you may also need an adjustable regulator lm317 to power the 555, and give a reference for the circuit.
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02GF74
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| posted on 26/3/18 at 09:13 PM |
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Let me see if I understand the requirement.
You want a circuit that switches on at a very narrow voltage range about a specific voltage.
A low power schottky diode has voltage drop of 0.4v.
A voltage divider with resistors and the diode can be set to give voltage tap off at v +0.2 v and v-0.2v.
Lets say you choose resistors so v is 3.85, the taps are 3.65 and 4.05 volts, is that good enough?
Then two two voltage comparators who output is 'anded' can the driver relay to switch any voltage or current.
The voltage divide would need an accurate voltage reference, it may happen that there are zener diodes that differ by. 4v or less that can be an
alternative.
So yes, it can be done, and possibly simpler to what I describe above.
FYI. Some zener voltages, choose one for lower voltage limit and other for upper, not adjustable as the schottky diode divider as that can have a
variable resistor.
2V 2.2V 2.4V 2.7V 3V 3.3V 3.6V 3.9V 4.3V 4.7V 5.1V 5.6V 6.2V 6.8V 7.5V 8.2V 9.1V 10V 11V 12V 13V 15V 16V 18V 20V 22V 24V 27V 30V 39V
See https://de.m.wikipedia.org/wiki/Datei:Fensterkomperator.svg
[Edited on 26/3/18 by 02GF74]
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gremlin1234
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| posted on 26/3/18 at 09:45 PM |
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quote:
or within very close parameters, 3.85V - it mustn't recognise 3.5V or 4.2V as being the same, so would need an accuracy of around 0.1V,
there are various 'dedicated' chips for changing lithium batteries that have exactly these parameters
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russbost
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| posted on 27/3/18 at 07:49 AM |
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Thanks, for your input guys.
If I understand correctly then I don't think the circuit based on the 555 chip will work, unless that ratio of 1/3 to 2/3rds can be more
accurately controlled - surely it wouldn't be specific enough to define between 4.2V & 3.85V?
02GF74 you have described the requirement perfectly, unfortunately I don't fully understand the answer! My electronics knowledge dates back to
the time of transistors rather than IC's & is limited by the fact that I've forgotten most of it!
I do basically understand what you are saying, but I have no idea how to implement it in a practical way, is there any possibility you could draw the
actual circuit you describe. For instance whilst I fully understand the concept of a voltage divider & an output that is "anded" I
would have no idea what I would need to achieve this
yours dunbly Russ!
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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timr1972
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| posted on 27/3/18 at 08:56 AM |
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There are ways of doing this with a simple comparison circuit, the 555 or you can start playing with PIC's. The analogue input of an Arduino
can measure up to 1024 steps giving quite a granular reading, you would just need to find the correct setting for your application.
This site has a very simple Arduino circuit that measures
voltage
Your ground reference would be critical and as an Arduino can be as small as an inch square it's quite simple to build. The only issue is
protecting the Arduino analogue input from any potential over voltage, spike etc on the sensing port.
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timr1972
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| posted on 27/3/18 at 08:58 AM |
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This is the Arduino Nano and your application is very simple but playing with the Nano could open a
whole load of other possibilities!
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russbost
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| posted on 27/3/18 at 09:52 AM |
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Really don't want to get into anythiung as complex as Arduino (would love to find the time to play with these things!)
Can anybody tell me does this
6sAA
OSwLKpZgh8L" target="_blank">Ebay link
do what I want?
I would need it to be adjustable such that it will switch on (or off) at anything over, say 3.75V & under 3.95V, I'm not clear if
that's what it can be programmed to do???
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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timr1972
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| posted on 27/3/18 at 10:12 AM |
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Looks like it does quite a lot Russ, but I think your original request was for 3.85 volts.
From the description "External signal input: (5~ 12V) or passive switch" I read as being outside of your scope.
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russbost
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| posted on 27/3/18 at 10:32 AM |
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Oh ***%$^£"!!!
I saw it was adjustable, but didn't spot the parameters, presumably I could amplify the incoming voltages & it would then work? Is it
feasible to amplify a dc voltage, or is there a way, say 2V could simply be "added" to the incoming voltage?
I thought this would be simple!
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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russbost
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| posted on 27/3/18 at 10:37 AM |
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Ok, would this
ebay link
amplify the input voltage such that I could use the voltage controlled switch previously linked to, or is my miniscule brain missing something else???
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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02GF74
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| posted on 27/3/18 at 10:42 AM |
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Depends on your definition of simple.
I will draw up circuit later this evening but need to know the voltage min and max for the switch to activate, if either of these is adjustable, then
need to know range.
Also an idea of the origin of the input signal and how fast it change: if it has noise on it, that can be smoothed but may delay response time to
switch.
I assume the circuit is powered from 12 v car battery.
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russbost
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| posted on 27/3/18 at 11:06 AM |
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quote:
Originally posted by 02GF74
Depends on your definition of simple.
I will draw up circuit later this evening but need to know the voltage min and max for the switch to activate, if either of these is adjustable, then
need to know range.
Also an idea of the origin of the input signal and how fast it change: if it has noise on it, that can be smoothed but may delay response time to
switch.
I assume the circuit is powered from 12 v car battery.
Ok, circuit is for a bike engined car. Long story short, modern setup where ECU reviews output voltage from gearbox sensor & should then turn on
the neutral light when neutral selected. However, the ECU does NOT simply provide an earth path, instead there is a varying voltage, as this
isn't the original dash if you attempt to connect a neutral LED (which won't work anyway) this then causes the ECU to throw a wobbly &
go into limp home, (I suspect it's interfering with CANBUS) with no neutral light connected it's fine, so I want to avoid the ECU
altogether & simply use the gearbox sensor output voltage to switch a relay/transistor or whatever to provide an earth path for the neutral LED
(12v miniscule current) - sounds simple enough you'd think?
The gearbox sensor outputs 4.2V in 1st. 3.85 in N & 3.5 in 2nd reducing gradually to .77V in 6th
I was suggesting having adjustment on the switching voltages simply in case my multimeter isn't giving dead accurate figures, but 3.75 &
3.95 would seem like a sensible range to start with
Does that all make sense?
Any help much appreciated
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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02GF74
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| posted on 27/3/18 at 11:16 AM |
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Hmm maybe, your dvm is averaging the voltage. Do you have any information about the sensor?
My gut feeling is that the signal is pulsed so not constant voltage.
I can draw up something but if pulsed then it won't work.
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russbost
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| posted on 27/3/18 at 11:25 AM |
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If it was pulsed would I not see that on the meter, it appears to give a consistent, continuous readout at a steady voltage, or are we talking about
it being pulsed at high frequency?
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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gremlin1234
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| posted on 27/3/18 at 12:22 PM |
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after a little searching, I have found it common to use a gear position potentiometer
https://www.race-technology.com/wiki/index.php/HowDoI/UseTheGearIndicator
as I said before lithium batteries have a similar requirement, and a search found this circuit
http://www.circuitstoday.com/lipo-battery-charger-circuit
might work if you:
connect input to pin 2, and remove everything to the right of the led.
edit:
reading this quote:
The gearbox sensor outputs 4.2V in 1st. 3.85 in N & 3.5 in 2nd reducing gradually to .77V in 6th
you only want it on at one voltage, and off if is either too high or log
so may need two comparitors, and a bit of logic
[Edited on 27/3/18 by gremlin1234]
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02GF74
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| posted on 27/3/18 at 02:15 PM |
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quote:
Originally posted by russbost
If it was pulsed would I not see that on the meter, it appears to give a consistent, continuous readout at a steady voltage, or are we talking about
it being pulsed at high frequency?
Not if at higher frequency that your dvm response.
For some reason I thought it may be signal from a rotating shafts but it can't be as rpm will come into play plus neutral would be different.
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timr1972
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| posted on 27/3/18 at 02:34 PM |
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At a high level two circuits measuring voltage with an AND is what I'd expect, logically:
Input one is biased to be HIGH when voltage is >3.65 and low in all other states
Input two is biased to be HIGH when voltage is <3.85 and low in all other states
Two HIGHs = Neutral light on
I'll let someone draw the circuit...........but this
is what I would imagine would work with the correct resistors to provide the relevant switching levels.
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DanP
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| posted on 27/3/18 at 03:57 PM |
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I would suggest either:
A non-inverting a schmitt trigger with a regulated supply voltage (i.e. one that stays constant no matter what the battery voltage is).
OR
An Arduino board (built in voltage regulator) with some simple code to read the ADC and apply some thresholding and hysteresis, there is bags of
reference code online, it will be easier than having a circuit made. There are plenty of people on here that could help, myself included.
Note: don't use an OP-AMP unless its in schmitt-trigger configuration as otherwise the output will oscillate when the input is just on the
threshold voltage.
For either circuit you will want a solid state relay OR mechanical relay with a bypass resistor OR a FET with one side connect to GND to control the
output circuit - depends on how much current you want to switch.
The reason you need a voltage regulator or something like a Zener diode as a reference voltage is that otherwise all of your trigger levels will
change with the battery voltage.
[Edited on 27/3/18 by DanP]
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timr1972
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| posted on 27/3/18 at 04:08 PM |
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The Arduinos I have lying around and could probably create one in an hour or so for you Russ if you want to try it out.....
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russbost
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| posted on 27/3/18 at 06:44 PM |
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Ok, many thanks for all the input, much to think about, I will buy some bits & have a play around, will let you know the outcome! (or should that
be output!) 
Thanks for the offer Tim, trying to do it with "off the shelf bits" but good to know I could fall back to Arduino if necessary
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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02GF74
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| posted on 27/3/18 at 09:19 PM |
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sorry not got round to draw this up in full, but the voltage comparator is achieved by 2 op-amps and "anding" is done by diodes and
transistor.
Vut and Vlt are set by resistor network to give the 3.7 and 3.9 or whatever threshold.
Best to have it powered from 9 or 10 V voltage regulator e.g. 7809 or 7810 device, - this will be used a constant voltage source for resistor
dividers to set vut and vlt.
response to Vin.
An 8 pin DIL dual op-amp will keep it small and simple:
in your case the LED for the neutral lamp will replace R , with a series resistor to limit current through the LED to the 9 v supply.
read about it here.
www.electronics-tutorial.net/analog-integrated-circuits/op-amp-comparators/window-comparator/index.html
[Edited on 27/3/18 by 02GF74]
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gremlin1234
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| posted on 27/3/18 at 09:43 PM |
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looks good, however, I disagree that the resistor divider reference should be powered by its own regulator*, it should use the same reference as the
pot on the gearshift. (probably raw battery voltage)
* yes if working with absolute values, but I don't think these are.
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02GF74
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| posted on 27/3/18 at 10:21 PM |
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Yes, maybe but the requirements specification did not state the voltage from sender would vary.
Easy enough to check by measuring neutral with ignition on, engine idling at engine at 2k rpm.
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gremlin1234
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| posted on 28/3/18 at 12:32 PM |
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I have been looking at typical bike circuit diagrams that use sensors like this.
and of course they are 3 wire sensors, +/- supplied by the ecu, and intermediate voltage returned to ecu.
so yes it will be feed from a regulated voltage ;-) so you could take it as an absolute voltage
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