Houston.. I got problem! - Page 1
Forum section: electronics / beginners

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 12:11:15 pm
content: Hi there(I did move this post to this area)I'm new here and just as good as average beginner in electronics. I'm a old programmer and done a lot of heavy stuff in that department. I know simple terms and understand somehow some basic concepts as transistors, relays, resistors, diode, capacitors and can I have made some simple logic gate's when I was younger.The problem I'm facing is I think a simple one for you guys. I have a a circuit for motorcycle to show what gear it is in, i.e. Gear Indicator. Ok. I bought this very cheap from China. Every thing works as it should on the bench.. that is, until I test it in the bike.The neutral wire was supposed to return 0v when in neutral (no gear), otherwise it returns 12v (for every other gear setting's) which is the main voltage on the bike. The problem is, the neutral sensor is is not returning 0v when the bike is in neutral. It's returning 0.5 something volts which is not low enough for the gear indicator circuit to trigger neutral. I haven't bother to contact the manufacturer but I did some simple resistors to ground check and with I think with 10ohm resistor I got 0.22V (if I remember right) and that did trigger the gear indicator properly.. but of cause that kind of resistor allows to much power drain and not usable when the bike is running in gears and the signal is 12V.So.. I must add some extremely simple way to kind of "mask" all low voltage to almost zero without affecting 12v. That is, at least all voltage below 1V should be masked down to as close to 0V (0.1-0.2V seems to be enough)Any idea how to do that without drawing current when signal is 12V?

author: danadak
author_rank: Super Contributor
timestamp: December 29, 2016, 12:24:16 pm
content: Have you got a rough schematic, even hand drawn, you can post ?A wire that is grounded, and still presents a voltage, eg. the .5 you areseeing, tells you either ground contact ohmic, not low enough resistance,or that there is a lot of current flowing in the ground wire and that X parasiticresistance develops the .5 V.Regards, Dana.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 12:27:02 pm
content: A diode drops 0.5 - 0.7 volts when conducting...

author: MrOmnos
author_rank: Frequent Contributor
timestamp: December 29, 2016, 12:52:10 pm
content: Post schematic.

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 01:01:51 pm
content: Quote from: danadak on December 29, 2016, 12:24:16 pmThanks DanaI think this sensor doesn't ground, it only drops voltage as low as it can (0.5v)Here is a picture of this sensor:I do however recall some kind of voltage drop circuit. Perhaps like this?

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 01:27:00 pm
content: Hi thereI did some google and found this side about "Universal Gear Indicator"Found this under section "Possible Improvement"Quote

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 01:49:15 pm
content: That is exactly what I suggested an hour ago...

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 02:22:20 pm
content: Quote from: PA0PBZ on December 29, 2016, 01:49:15 pmI think you are misunderstanding something.. this quote I used is of the page I linked to is not what I'm using and I'm not designing this circuit, I bought this item from China in sealed structure or box as can been seen in this image.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 02:34:22 pm
content: Ok, let me be more specific: Add a diode to the neutral wire like this ------wire-------->|-- , it will 'subtract' 0.5V from the voltage on the wire.

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 02:53:43 pm
content: Quote from: PA0PBZ on December 29, 2016, 02:34:22 pmAnd what will happen when the wire transfer 12v ?

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 03:06:52 pm
content: Quote from: Garrinn on December 29, 2016, 02:53:43 pmThen 11.5v will end up at the other end, enough to do the job.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 03:11:53 pm
content: Quote from: PA0PBZ on December 29, 2016, 02:34:22 pmNever mind, I just realised that the neutral wire is pulled to ground, it isnotsupplying any voltage. Forget what I wrote.

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 03:14:00 pm
content: Quote from: PA0PBZ on December 29, 2016, 03:06:52 pmOk.. I'm not sure I understand this to full.Ok, let's say I will buy 12v diode 0.5A wich will withdraw 6W when the voltage is 12w and drop voltage to 11.5V. The real question is, will that voltage drop still be 0.5V when the wire has total 0.5V also?I have always thought that diode was kind of resistor. And voltage drop therefor would be linear with voltage.. but as I said, I'm a beginner!

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 03:21:23 pm
content: Quote from: Garrinn on December 29, 2016, 03:14:00 pmSee above, I just realised that the diode will not work. Look at the diode as a one way device, current will only flow in one direction and it needs 0.5v to open the portIf you reverse the positive and negative it will stay closed.

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 03:27:22 pm
content: Quote from: PA0PBZ on December 29, 2016, 03:21:23 pmHmmm... if it needs 0.5V to open and (withdraw power) how on earth would that be usable to drop 0.5v to close to zero which is my main goal?This sensor is loaded 12v regular by this one wire. When it detects neutral, it voltage drop to 0.5v That drop isn't enough for this gear indicator, if it would drop the voltage to 0.2v it would be enough, as I explained in my first post.(Modified). And reverse current isn't any part of my problem, so resistor would be enough.. but as I described in the orginal post, it would withdraw to much power because it have to be so "small" to lower 0.5V to 0.2V

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 03:34:59 pm
content: Yes, like I already said I realised a bit late that the wire was not supplying any voltage so the diode trick will not work.You probably have to look at the circuit that detects the voltage and make a modification there, or you could try the diode trick in the wire going from the indicator to ground. That way you will raise the point where the indicator thinks is ground by 0.5vSo, ground wire from indicator box ------------------>|----------------- ground.

author: jm_araujo
author_rank: Regular Contributor
timestamp: December 29, 2016, 03:48:01 pm
content: As I understand the neutral light is pulling current from the switch and increasing it's voltage to 0.5V.Raising the ground of the gear indicator can create a lot of other problems.The simplest without drawing too much current I think is using a relay. Coil to +12V and the neutral switch. Common to GND, NO to gear indicator. Use a generic small automotive relay.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 03:51:03 pm
content: Quote from: jm_araujo on December 29, 2016, 03:48:01 pmSince this is made for a motorbike I don't think it would create a problem stealing 0.5V from the supply voltage, it's not that it is a regulated 12V anyway.It's certainly the easiest way and it will not hurt to try.

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 04:04:34 pm
content: Thanks guys for the effort.Just to clarify.. here is simple schema I did draw.As you can see it's only one wire to the sensor. I reckon it's power is controlled from the ECU as it is only one wire. How, I don't know.The problem is I need almost zero volt from this sensor so my gear indicator can show me neutral (zero sign)The sensor is always 12v when gear is 1..6 but 0.5v when gear is in neutral.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 04:58:09 pm
content: And this is what you will get adding the diode:

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 29, 2016, 05:05:38 pm
content: From the picture and the description, the "sensor" is a switch that takes the circuit to ground only in neutral.Make sure your grounding to your motor/transmission is adequate by tightening the ground lug. This can cause a problem such as yours.PEACE===>T

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 05:23:01 pm
content: Quote from: tpowell1830 on December 29, 2016, 05:05:38 pmThanks!I did check that indeed.Why?You see.. when I was wondering where I could get the ground for the indicator I saw two black wires (ground's) fasten to bolt on top on engine close to the neutral sensor.. the bolt was so stuck I could'nt move it easily.. so I did fetch the ground for the indicator from other position close by (from the engine also).In fact I do not understand how single wire sensor works at all or as this one does. It has 12V when bike is in gear. Those 12V must come from some power source. When the sensor sense neutral all the sudden it got almost zero volts.. so my guess is ECU is controlling the voltage and as you can see from this schema it is rather complicated how this information is used in this start system.

author: jm_araujo
author_rank: Regular Contributor
timestamp: December 29, 2016, 05:44:02 pm
content: You're over-complicating things.The motor body is all grounded, that's the second "wire" to the sensor. The switch shorts the wire to ground when in neutral.According to that schematic, when in gear the switch is open and will see the 12V from the connection 2-3-4-5-6-7. When in neutral it will energize the relay 6 allowing you to start the motorcycle.That diagram is missing the connection to the neutral indicator light, that also energizes the wire (fully annotated wiring diagram in here:http://circuitswiring.com/circuit-diagrams/2/2011/06/complete-electrical-wiring-diagram-of-yamaha-yzf-r1.jpg,neutral switch located middle-up)

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 05:54:46 pm
content: Quote from: jm_araujo on December 29, 2016, 05:44:02 pmThanksGreat diagram.. I own the service manual but this (vidal) remarks are missing.And.. yes, I did suspect the sensor did shortcut the power to ground.. and by that, lower it's voltage and "drain" it's source so to speak. But had some tough thoughts about the draining part..But that explain why I do not get absolute zero value.So.. the problem still stands. I will try the diode method, that is, drain this wire to ground through diode.. any recommendation about size of diode? And will it lower my 0.5V to 0 as PA0PBZ suggested?

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 29, 2016, 06:02:48 pm
content: Can you check the diode marked #7 in your circuit? This could be bad. Check all of the diodes at bottom of your drawing to see if they are shorted or closed.PEACE===>T

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 06:15:50 pm
content: Quote from: tpowell1830 on December 29, 2016, 06:02:48 pmThanks.I don't know how easy it is.. will look into it, but this part (diode and the clutch switch) seems to have some affect on the voltage I get in neutral as if I use the clutch level, the gear indicator shows sometimes 0 as for neutral.. that is, is working when I use the clutch.. but not always. By repeating squeezing clutch level it will eventually show 0 almost in every case.. but not always.

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 06:26:38 pm
content: One idea..Is there some kind of transistors which only works for specific volt range?In my problem, will only work at 0.x - 1.x volt range? If so I could switch to ground to the indicator?

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 29, 2016, 06:44:57 pm
content: QuoteThe clutch switch and stand switch are in parallel with the neutral switch. This makes sense. Check the diodes if you can.The problem is simply that your neutral switch is either dropping the voltage (0.5V) or there is a problem in that part of the circuit. Take your meter on DC Volts in the lower range and measure the volts from the chassis at the point where the neutral switch is located and to the negative pole of the battery while the transmission is in neutral. If you see a voltage there then it is a grounding problem between the battery and the transmission. If the voltage is 0, then the problem is either the voltage drop of the neutral switch, which no additional diode will fix, or there is a bad connection or bad component elsewhere.PEACE===>T

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2016, 06:52:02 pm
content: Quote from: tpowell1830 on December 29, 2016, 06:44:57 pmA diode in the ground lead of the indicator box will lift the ground/reference to 0.5v and cancel out the 0.5v on the neutral wire.

author: Ian.M
author_rank: Super Contributor
timestamp: December 29, 2016, 07:07:36 pm
content: However there is no guarantee that the neutral switch closed voltage will stay stable at +0.5V. A 12V reed relay is a much safer option, and IMHO is worth it for anything better than a rat-bike with Lucas electrics!The reed relay should be connected: coil wired between +12V supply and neutral switch, contacts wired between module switch input and module Gnd. A pullup resistor to +12V may be needed at the module input. 1K2 1/2W would be suitable and would provide a 10mA 'wetting' current to the reed contacts.Take care to get the coil polarity correct - reed relays can include an integral anti-parallel diode or magnetic bias and polarity reversal may damage it or just not work.Once its tested, pot it in epoxy!

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 29, 2016, 07:14:40 pm
content: Quote from: PA0PBZ on December 29, 2016, 06:52:02 pmIt probably will work, but it doesn't address the main problem. If there is a bad connection, what happens when it gets worse and there is a 1 volt drop? My key word there was "fix" or repairing the existing problem. A diode on the ground lead of the indicator box will also cause a useful voltage of only 11.5 volts for the indicator box.PEACE===>T

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 07:38:01 pm
content: Quote from: tpowell1830 on December 29, 2016, 07:14:40 pmCorrect me if I'm wrong.. but isn't some kind of logic to have "left over" voltage if the neutral switch just shortcuts 12v wire to the ground?

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 07:43:44 pm
content: It looks like I'm not the only one with this problem. Found thishere. Relay (Mosfet) is somehow in my mind when I mention transistor here before.QuoteModified..Did find this inother forum.Quote

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 29, 2016, 08:43:54 pm
content: I guess that leaves me to ask: Where in the circuit did you tie your indicator? This should be tied in near the neutral switch, on the cathode side of diode marked #7. If you tied in on anode side, then there is your 0.5 volt drop.PEACE===>T

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 08:52:37 pm
content: Quote from: tpowell1830 on December 29, 2016, 08:43:54 pmIt was about 4-5" from the sensor. Tiny loop I could solder to.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 29, 2016, 09:07:01 pm
content: Quote from: Garrinn on December 29, 2016, 08:52:37 pmIf you are sure that there are no branches or lumps in the wire that could be inline diodes, that should be okay.The relay that he mentions will work if the coil resistance is pretty high, otherwise you will have the same problem with the relay not actuating. There is no "left over" voltage from the 12V from the indicator because it probably has a resistor in series with that line that should be pulled hard to ground. However, if the neutral switch has a high resistance when closed, then there will be a voltage drop. Most switches are useful only if they have a low resistance when closed, but in this case, it was not necessary to pull the start relay to ground.I have added a circuit in your diagram that should fix your problem.Choose a 12 volt DC relay that has a higher resistance coil for R1.i made a mistake connecting to the plus side of battery, you should connect to base of fuse between #4 and #5.PEACE===>T

author: Garrinn
author_rank: Contributor
timestamp: December 29, 2016, 11:48:19 pm
content: Thanks againI understand bikers indention to use relay for grounding the indicator.. but can't figure out how he did it actually. As 12V is the voltage when gear is NOT neutral. That's part of it why I asked about way to mask voltage below around 1v and why I asked about if there where a way or type of transistor (mosfet) which work in specified volt range as 0.2-1VI don't have knowledge to figure out how I can use relay to open ground with the neutral sensor as the sensor has 12v default and 0.5v when I need it to trigger the relay. It can't be ground all the time, only when voltage is 0.5vOne way would be to "grab" the neutral light, from the ECU I guess and use that as a trigger for mosfet or relay for grounding the indicator neutral wire.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 30, 2016, 12:17:52 am
content: The sketch that I showed on your drawing would work. I hope you sort it out. Over and out from Houston.PEACE===>T