A very basic diode question.

Thread Starter

MazdaCarnage

Joined Apr 26, 2020
20
Electronics might just be the most complex thing to learn, most things mechanical can be learned and understood through theory alone, no need to bench test...
I have read about and used diodes but I can't figure out the answer to this question without practice.

I want to have 4 LED lights identifying status, lets call them 1,2,3,4.
Based on settings and situations different LED's will be on, LED 1 is only a setting identifier, LED 2 can be a setting identifier but is also a situation identifier.

I want LED 1 and LED 2 to be powered by the same DC + power source but I want LED 2 to have a second power source that doesn't turn on LED 1.

If a diode is place between LED 1 and LED 2, LED 1's power source is off and LED 2's power source is on will LED 1 flicker or light up?

This is for automotive application, here is a diagram for LED control:


View attachment 306219View attachment 306219
 

dl324

Joined Mar 30, 2015
16,677
If a diode is place between LED 1 and LED 2, LED 1's power source is off and LED 2's power source is on will LED 1 flicker or light up?
If you're referring to typical automotive voltages, diode leakage won't be sufficient to turn LED1 on.

There are two links to your attachment; neither work.
 

panic mode

Joined Oct 10, 2011
2,670
attachment link is broken. if i understood correctly you want something like this:
1698787252415.png
as long as voltage drop across diode between two LED branches is insignificant for the circuit, this can work, otherwise turning on "A+B" will have LED "A" dimmer or not light at all. this is why diode need to be away and not directly across LEDs.

or if powering just one of LED from different sources, diode OR (or half of it) will do. something like
1698787651154.png
 
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MisterBill2

Joined Jan 23, 2018
17,790
OK, now I see the wiring diagram, which may contain the logic, or maybe not, interpretation is a challenge.
What I believe I see is a very difficult to implement scheme to verify a required set of states, implemented by standard automotive relays. There are certainly much simpler ways to do this. It would keep the string of lights illuminated as each state was added to the ready list. Adding the "one light at a time" function could be added with more relays. And no diodes for either scheme.

But this looks like a case of the TS having already decided a scheme that they want and now requesting help in making an unworkable scheme work.

The whole system appears to be a way to verify every step getting ready for launch in a dragster race. Or maybe a street racer run.
 

Thread Starter

MazdaCarnage

Joined Apr 26, 2020
20
But this looks like a case of the TS having already decided a scheme that they want and now requesting help in making an unworkable scheme work.
The only part of the set up that I am uncertain about is the diode separating led 2 and led 1, just trying to figure out if I it will work or I should come up with a different set up than the diode before I put everything together, would rather not do it twice. Although I am opened to suggestions.

The whole system appears to be a way to verify every step getting ready for launch in a dragster race. Or maybe a street racer run.

It's similar, but LED's are just a setting status identifier (like P.R.N.D. on an automatic car), the system is to control 3 stages of boost.
There is a 3 way switch (LAUNCH, OFF, STAGE 1).
Launch uses a hall sensor at the shifter arm and earth magnets to identify 1st gear, a solenoid shuts off boost control and only wastegate boost pressure is run.
Stage 1 shuts off boost control all the time.
Off is stage 2 or 3 boost depending on the button position on the shift knob.

No two numbered LED's are to be on at the same time.
When Launch is selected on the toggle switch I want the LED (launch) to stay lit all the time and have the appropriate stage identification led lit up also, 1st gear = stage 1LED. neutral, 2, 3, 4, 5, R = stage 2 or 3 LED depending on settings.

Launch = Launch LED + The current boost stage LED
Off = Stage 2 or Stage 3 LED only, there are several fail safes that will cause stage 3 to default to stage 2 (Low tank level, low tank pressure, wrong air fuel ratio and knock control.)
Stage 1 = Stage 1 LED only

The car is a FWD street car, this setup is to try and control wheel spin at the drag track and to easily know what settings are selected and if they are working.
This is the only way I could think up to automatically change boost settings with basically manual boost controllers without running an expensive controller that monitors speed and rpm to know what gear the car is in and run gear based boost control. The stage 3 boost control button is on the shift knob because I didn't want to reach for it, I wanted it on the steering wheel but adding a clock spring to the factory column is not possible, well maybe it is but a lot would require changing. I have to reach for the shifter between every gear but none come with on off toggles, so I carved a shift knob and installed a button, didn't like the angle so I customized shift rod assembly and throw, added a hall sensor and magnet, the shifter boot requires a zipper to connect the shift knob wires to be able to screw on the shift knob and not break the wires. Normal shift boots won't fit, some large aftermarket's might but I am going to stitch my own. Like rolling a snow ball down a mountain the simplest idea can get out of control fast.

There are certainly much simpler ways to do this.
Tell me about it. This is just a small part of the total system I must be up to 15 automotive relays for the crap I have added to the car, the horn set up has 4 relays (including the factory relay) to operate it. I looked into and tried learning to program an arduino controller but I couldn't visualize the function of operation through the programming, definitely something I would need to purchase and work with to learn. I like to come up with and idea, research and learn, plan, design and finally purchase whats required, assemble and install.
This all started out normally, you add a device to a car, you add a relay. I was adding a lot of things to the car so I decided I want a relay/fuse block, I have added stuff to cars in the past one thing at a time and it results in a pain, even if you use connectors and wire loom it all becomes a problem when removing, why not design one large harness that connects to the fuse and relay panel and to every device just like the factory stuff.
From there it all grew into a twisted primitive type of "control system" that all defaults to factory function and all connects to one wire harness.

OK, now I see the wiring diagram
I like to think of it as a function diagram of that part of the system so I can remember.
The actual wire diagram has is just connector pinouts and paths, there is so much stuff added to the car to draw wires in the wiring diagrams.
 

DC_Kid

Joined Feb 25, 2008
1,072
I want LED 1 and LED 2 to be powered by the same DC + power source but I want LED 2 to have a second power source that doesn't turn on LED 1.
It's all one source, you just switching them independently.
It's probably easier if you sink switch the LED's, provide power to all LED's and then you inline a "switch" on the negative terminal of LED.

Relay #3 wiring in post #5 does not look right, assuming "fuse" is from batt. Arrows on the wires are confusing. As-is it looks like fused power connects to relay coil, through a "switch" and then loops back around through an indicator LED.
 

Thread Starter

MazdaCarnage

Joined Apr 26, 2020
20
Relay #3 wiring in post #5 does not look right, assuming "fuse" is from batt. Arrows on the wires are confusing. As-is it looks like fused power connects to relay coil, through a "switch" and then loops back around through an indicator LED.
Only the red wires are 12v+ all the other colors are ground signals so the relays all pass ground not 12v+, all the devices (horns, fog lights, boost solenoids, water injection solenoids, air pump...) are constant + / switched ground operated the same way the factory lights, fan and accessories are turned on and off.
Fuse # 7 is an ignition switched fused 12v+ it goes straight from the fuse to the relay 3 coil.
Relay #3 only receives 12v+ through pin 86 (coil)
Pin 87 (IN) is a ground signal
Pin 30 (N.O.) sends the ground signal to Stage 1 LED
Pin 87a (N.C) sends the ground signal to stage 1 boost solenoid to open it and ground signal to Relay 4 pin 87
Pin 85 (coil ground) is activated by the 3way toggle switch, when launch is selected the ground signal passes through the Hall sensor at the gear shift rod, when stage 1 is selected, the toggle switch ground goes directly to the coil.

If I could find a reliable normally opened solenoid valve that can flow enough air for the boost control system I could wire it differently and not have to have it powered on most of the time the car is running, but the solenoid is a 34year old factory turbo solenoid, it is designed to have a straight through passage and bleed off an adjustable amount of air, I closed off the straight through passage and enlarged the adjustable passage and turned it into an simple opened closes solenoid valve, these solenoids live bolted to a turbocharger and are powered 90% of the time, they don't get warm when left on and never seem to fail.

The one thing missing is the 12v+ going to the toggle switch is ignition switched and fused.

Would this post be accurate in relation to the diagram I posted?

If you're referring to typical automotive voltages, diode leakage won't be sufficient to turn LED1 on.

I'm going to have to disagree. I think Stochastic Calculus or maybe the Calculus of Variations just might leave electronics in the dust.

https://en.wikipedia.org/wiki/Stochastic_calculus
https://en.wikipedia.org/wiki/Calculus_of_variations
I believe you.
 

DC_Kid

Joined Feb 25, 2008
1,072
I can't quite follow the description vs diagram.

Relay #3, Fuse and Ground pins is the relay coil?
Then I assume the no-label pin is the throw (wiper) to NO and NC, and with #3 off the #3 wiper is NC'd over the coil of relay #4 ?
Somehow it looks like you loop +12v to the ground side of LED's when relay #3 puts wiper on the NO pin.
 
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MisterBill2

Joined Jan 23, 2018
17,790
For starters, the volume and complexity and the number of relays can be reduced a whole lot by changing to 4PDT relays that have four sets of contacts and each relay occupies half the volume of the automotive cube relays. They can be purchased with 5, 6, 12, and 24 volt coils. In addition, interchangeable relays are available from multiple brands.
The one relay can be wired to each signal/condition circuit, and the logic to decide which LED is on can be thru a string of contacts. THAT can make the whole project much simpler, smaller, and possibly less costly AND NO DIODES NEEDED!
And no consideration about DC leakage lighting LEDs.
And the final advantage is we will not need to see a wiring diagram but rathera circuit schematic, so that the logic function will be simple and easy to see.
 

Thread Starter

MazdaCarnage

Joined Apr 26, 2020
20
I can't quite follow the description vs diagram.

Relay #3, Fuse and Ground pins is the relay coil?
Then I assume the no-label pin is the throw (wiper) to NO and NC, and with #3 off the #3 wiper is NC'd over the coil of relay #4 ?
Somehow it looks like you loop +12v to the ground side of LED's when relay #3 puts wiper on the NO pin.
I did mix up pin 30 and 87 in my description.
The relay layout is the same for all relays in the diagram, Ground pins are black and 12v+ pins are red, I did mix up the position of 87 and 87a in all my diagrams
I labeled the relay pins:

666 Wiring 5-Page-92.jpg

When relay 3 coil is OFF ground passes through the normally closed pin 87a, it opened stage 1 solenoid and allows ground to pass to pin 30 IN of relay #4.
When relay 3 coil is ON ground passes through the normally opened pin 87 to the ground side of LED stage 1.
 
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MisterBill2

Joined Jan 23, 2018
17,790
Consider how easy and simple this would be if it were shown as a commented ladder diagram. It would be simple to follow the logic and not too bad to do the actual wiring, even with 4 pole double throw relays. Which probably cost less than the single pole double throw automotive cubes with the 30 amp contacts that are not needed for lighting LEDs. The relays could even be put in solder-tail sockets that would allow quick replacement when they wore out after 10,000 operations.
 

Thread Starter

MazdaCarnage

Joined Apr 26, 2020
20
For starters, the volume and complexity and the number of relays can be reduced a whole lot by changing to 4PDT relays that have four sets of contacts and each relay occupies half the volume of the automotive cube relays. They can be purchased with 5, 6, 12, and 24 volt coils. In addition, interchangeable relays are available from multiple brands.
The one relay can be wired to each signal/condition circuit, and the logic to decide which LED is on can be thru a string of contacts. THAT can make the whole project much simpler, smaller, and possibly less costly AND NO DIODES NEEDED!
And no consideration about DC leakage lighting LEDs.
And the final advantage is we will not need to see a wiring diagram but rathera circuit schematic, so that the logic function will be simple and easy to see.
Thank you for the suggestion, I do appreciate it.

If I add a small N.O. relay to the huge number of relays I am running and replace the diode with it and wire it:
Relay path replaces diode path, coil + from the launch button + and coil - from the #3 relay N.O. pin 87 (Only need one of those coil signals to work this) the launch LED could never get + voltage trickle when stage 1 is selected.

I do have some DPDT building control relays and sockets, the ones that take the orange relays, I would rather not use these types of relays to control any car systems, I don't like the way they wire up, they kinda suck at clamping wires properly.
These types of sockets:
70229908_right.jpg
Would have to find a spot to run din rail to mount the relay and install connectors for the wires at the relay, using a screw driver under the dash to connect the relay isn't practical,


The LED indicators are an after though or added thing I figured I could do with the relays already used for the added systems on the car, relay #3 would be a 4 pin normally closed automotive relay that would almost always need to be on or the same relay with pin 87connected to nothing.



This is or was a no budget build, most everything used I already had and much of it is wired.
I drew out the fuse/relay box on paper, then copied it to a diagram (with some mistakes), purchased the box and wired most of it (using the hand drawn diagram), it sits behind the glove box next to the dash fan in front of the hvac accordion, it bolts to a stainless bracket I made that bolts to two factory studs in the dash.

666 Wiring 5-Page-1.jpg

I could not fit the 100amp relays in the box so I made a bracket to mount them to the firewall.
Some of the other relays I used are factory engine bay relays, there is a relay bar on the firewall with 6 slots but the car only uses 4 so I added two there.

Test fit in the old car:
20200823_192634.jpg
The relay box cover fits but I don't need to run it.
Every wire is oversized, if it needs 16gauge it gets 14 gauge...






Stage 1 boost setting was designed for driving in snow. But after spending 6 years building it I decided not to drive it in the winter, which is ironic because the reason I chose FWD to modify is because I don't like the power losses of AWD set-ups and RWD cars are dangerous in the snow. Although this will be the first build car I don't drive in the winter in the 25years I have been modifying and driving this brand and model of car, if I'm going to garage it for the winter I should have built a turbo V8 rear wheel drive, some LS blocks in factory form can make close to 1000hp. I always believed if you put all that effort and time into building a car you should get to enjoy it 365 days a year but the liquid sodium brine they spray the road with in the winter won that battle.

Live and learn.

But these FWD cars have great handling, are easy to work on, seriously under engineered (the engine, transmission, axles can handle at least 3 times factory torque in stock form), these cars where built in 1987/1988, I've been driving them since 1998 and have never had to change an engine sensor or relay on any of them, I have use the 1988 engine solenoids and sensors to replace the failed crappy unreliable parts on cars built in the last 20years.
This one is a 4door version so it's a sleeper and very quick, the bar for fast is set high and climbing all the time, some hyper cars are at or above 2300hp with a top speed battle that's up to 330 mph (sounds a lot faster in kph 531km/h) unusable top speeds so they can be the fastest, some day someone will build the SOD 1200 with a top speed of 740 mph, the following day it will be banned.


Launch is for the drag track and red lights.

-------------------------------------------------------

I really need to buy a breadboard, had one in the 90's but can't find it in my basement.
 

Thread Starter

MazdaCarnage

Joined Apr 26, 2020
20
Relays 8, 9, 10 are necessary because the adjustable pressure switches I purchase are rated for 500mA max and the gem controls Solenoids are well I am not exactly sure, they are 24/50/60 7.6W and 150/12 (assuming DC), can't find 150/12 under solenoid coil on the internet and these Gem solenoid part numbers don't relate to any solenoid valve on GEM controls site.
Solenoid coils can run on AC or DC current and live a lot longer at DC 12V than AC 24V.
So if it's 7.6W at AC 24V it should be 633mA at DC 12V. If its150W at DC 12V than it would be 12.5A, either way the pressure switches aren't rated for the coil amperage.
 

Thread Starter

MazdaCarnage

Joined Apr 26, 2020
20
Many OVER-powered cars
There is no such thing, only UNDER-qualified drivers.

Many OVER-powered cars launch from a green light and are T-boned by another car sneaking through their amber light.
Getting hit by someone running a red light doesn't require an "over powered" car or to launch. You must always watch the behavior of the oncoming traffic while watching for the light to turn green, there are a few seconds between the lights switching, more than enough time to observe and confirm all cross traffic has come to a complete stop before the light turns green and to react to the green within 1second (at any rate of acceleration), any longer is disrespectful to everyone behind you.

So I say the only way to get T-boned in an intersection is to not pay attention while driving.

Once years ago while sitting at a light with my signal on to turn right and my car angled towards the right, a kid in a loud Honda Civic pulled up to my left at the intersection. He kept revving his motor and looking at me, I kept pointing at the cop car waiting at the light right across from us, light turned green, I turned right and he took off making an underpowered racket as the cop put his lights on turned around to pull him over.

Everyday I see people at red lights in front of me playing with crap in their car or talking to their passenger, not watching the light or traffic, finally they notice the light has turned green, they don't check for cars and just go.

So you can be an intense driver planning to launch or a lethargic driver pausing at the light it doesn't matter if you don't pay attention at intersections you have a chance of getting T-boned.

But my experience is that intense drivers with performance cars pay a lot more attention and respect risk a lot more than lethargic drivers that don't pay attention and just follow the car in front of them. The slow drivers are the most dangerous.

This comment sounds like it's based another one of societies misguided lies to send morons on witch hunts, fast cars are the epitome of evil, smokers are the epitome of evil.
The cold hard reality is that the masses in modern day society, the law abiding, rule following, go to work everyday, pay taxes and have kids majority of population on this planet, conditioned to consume and simply exist are the actual epitome of evil.
I was born in 1973 and there was already to many people on this planet, I did my part and never had kids.
Next time you're sitting in heavy traffic imagine it's because our governments tax farm and the more live stock there is the more revenue they collectively generate, no matter the cost to the planet or quality of life of the live stock. Quality of life does not equal years of life, it equals how much you lived during the years you had, everyone has had to settle for less every year.
 

Audioguru again

Joined Oct 21, 2019
6,608
Most of the OVER-powered cars are too noisy with their mufflers removed (the backfiring sounds like a gun fight), their windows are blackened so the hidden driver cannot be seen waving to proceed or to stop by other drivers and of course their cars are lowered. Some of the cars have their pollution controls removed so they stink.

I am an old senior living with an excellent Quality Of Life and I am healthy enough to continue for many more years.
 

Thread Starter

MazdaCarnage

Joined Apr 26, 2020
20
Most of the OVER-powered cars are too noisy with their mufflers removed (the backfiring sounds like a gun fight), their windows are blackened so the hidden driver cannot be seen waving to proceed or to stop by other drivers and of course their cars are lowered. Some of the cars have their pollution controls removed so they stink.

I am an old senior living with an excellent Quality Of Life and I am healthy enough to continue for many more years.
I would like to propose an alternative way of phrasing things. "Most annoying modified cars here where I reside are too noisy..."
The new corvettes, mustangs, Lamborghini's ... are extremely quiet, you can barely here them next to you at a light, you can't hear Tesla's at all, these cars are a lot more powerful than the cars your talking about.
Dark window tint is an Ontario problem, I exist in Quebec (would say live but that would be stretching the word), there are no dark tints or loud mufflers here, the cops are all over that and expect every car, even older ones to be as quiet as new cars.
My search for a quiet 3" universal exhaust has been intensive, you could bolt a shiny chrome tip muffler to the back of an electric car here and you would get a loud exhaust ticket, if it doesn't look factory they ticket.


Sounds like you have an issue with Ricers, I am a Motorhead, I won't sacrifice function, reliability, durability, performance or safety for looks or sound, I use 1" lowering springs on all my builds because of the increased performance but use coil spring seats and mount bearing spacers to raise the car back up 1/2" to clear snow, speed bumps and potholes (we have a most impressive collection of those here) without slowing down. The cars in 1988 had a lot more ground clearance than those built today therefore my car still has more ground clearance than new cars. Lowering a car too much will sacrifice handling, I bought one of these cars it had dark tinted windows, on dark knights you had to put them down to look for cyclists and pedestrians I didn't like it, not tinting the windows on the previous car attracted no attention but I will do a light tint on this build to lower interior temps and UV damage.

I run the full factory emission system with aftermarket catalytic converters. But I have worked on and drove some cars with all emission controls removed and they just smell like they are running rich at worst, improper tunning and mods for the current ECU's fuel and ignition map are what causes exhaust to stink, propane fueled vehicles seem to be the worst when it comes to unproperly maintained emissions systems, they aren't checked often enough.

The no muffler sound you are mentioning, if it's a recent thing it's usually on BMW's the Ricers are running a new engine recode that messes with ignition timing and causes that noisy backfiring, not good for the engine or performance, unless you hear a car sound like that and take off and disappear, it's a ricer craving attention but not an OVER-powered car, many of these modifications make the cars slower over all than factory with some gains near peak rpm. You live in Ontario a province in which most people can't safely operate a vehicle, by definition I would say overpowered is any car the driver can't handle at full throttle or know when not to use full throttle and by that definition most cars sold to canadian drivers are over powered.

These cars I drive I will have you know have no turbo lag so at 1/3rd throttle leaving a light can spool the turbo to set boost but make 1/3rd or less the power, the turbo starts to spool keeping up with traffic, limiting boost limit isn't just to control wheel spin and race.

Although I feel your and my definition of quality of life may be different I am very happy you have lived life to it's fullest and are looking forward to enjoying many years to come.

And if you where that happy and Zen you would let these kids live a little, before they have to die a little inside like most canadians and conform to the though that eating the food you like, taking walks in the park, living a long time but retiring after you already gave up your dreams, a falls sense of security and following the rules is "Living". I hope you made some noise and stirred things up in your heyday in your own way.

when they wore out after 10,000 operations
Does 10 000 operations sound like a lot to you, in automotive terms if this was the relay operating the stage 1 relay or the stage 1 solenoid and I only drove to work and back 250 times a year, there are 40 lights and stop signs in both directions, here in Canada lights are timed to be red from light to light to increase fuel tax revenue and keep the population busy, I would say 80% of the lights are red when you get to them, so in a year (not including heavy traffic, buses, or any other driving I do) I put the car in 1st gear over 16000 times a year and in other stopping and driving that's 2 relays a year? not practical, reliable, environmentally friendly or economical.
The 34year old relays I am using on this car open and close twice per gear in every gear every time you shift they last hundreds of thousands of miles, calculate how many times a standard car shifts on average over the span of 200 000miles, that's the beginning of a life span, how many times does the brake light relay operate?
10 000 operations in automotive terms is most unreliable.
 
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