OK to feather my thumb throttle?

[PCeBiker]

The 1K ohm potentiometer shown in the last pic is the same one I use and it works fine. Your controller may be different though.

That's good to know. I haven't tried that potentiometer yet.

When I replaced the 2.3K and 2.7K ohm fixed resistors with the 5K ohm pots, it took a lot of experimenting to get the results I wanted.

I was using them to try find where the throttle faults are below 0.8V and above 4.2V

I gave up measuring voltage. It's what the controller wants to see that's important. You've got the right idea by wiring the throttle circuit to the breadboard.

I did manage to get it working without the throttle fault below 0.8V but I couldn't get full throttle.

Are those 5K ohm pots on your breadboard good quality? A "noisy" pot, or one with flat spots can really foul up your results. I use these:

They are the same brand as the 1K .

I have no idea about those little potentiometers.
They've been in my electronics box since the early 80's.

Those better quality potentiometers in the link are $20 for a pair with the shipping, and I wouldn't be using them in the final circuit.

It doesn't really matter if the cruise control dial has a dead spot at start or finish of the rotation, but that would be really annoying with a throttle.

As long as I can get to full throttle, I'll be happy.

So, I'll start with the little 5K potentiometers to see if I can get them set at just after the "throttle fault" at ~0.8V and just before the "throttle fault" at ~4.2V and see if it works.
If not, I'll replace them with resistors and try again.
I intend on using resistors for the final circuit anyway

I can try applying voltage directly from my power supply to my controllers' throttle input and see what happens as well. That way I can see exactly what voltage the throttle faults kick in at.

 

[PCeBiker]

It's Working !!!

When I replaced the 2.3K and 2.7K ohm fixed resistors with the 5K ohm pots, it took a lot of experimenting to get the results I wanted.

I gave up measuring voltage.

I ended up measuring the voltage and replaced the 2.3K and 2.7K ohm fixed resistors with a single 330 ohm resistor.

I used your schematic and drew my fancy schematic on top of it.
(Excuse my fat finger drawing on my smartphone. )

So my wire colors are all mixed up and stupid and I found out that when my signal wire was at 4.2 volts, my throttle was at zero.
At full throttle the voltage went to 0.8 volts and didn't register a throttle fault until it hit 0.4 volts.

My controller is supplying 4.35 volts and I could feed it directly into the throttle signal wire without a throttle fault, so I didn't need a second resistor.

I remember someone posting that when the negative wire to their throttle broke off, their throttle went to maximum, so I removed the negative wire with the bike running, and the throttle shut off.
Same thing when the positive was disconnected.

I'm pretty sure that's a safety feature with my KT controller, and that's why full throttle is at minimum voltage?

If I turn on my e-bike with the throttle on, it registers a throttle fault as well as when the voltage drops below 0.4 volts.
It has the throttle input listed on the controller as 0.8V- 4.2V, but that's not true. Anything above 0.4V is accepted by my controller.

There are dead spots in my potentiometer at the beginning and end of the rotation that could be eliminated with a second resistor and a value higher than the 330 ohm resistor that I chose, but I don't mind the dead spots as long as they aren't in the middle and I know that I'm getting maximum throttle.

The 1k ohm potentiometer/motor controller works very well and has a really nice feel to it.

I tried to connect both my potentiometer and thumb throttle to the throttle input in parallel and it didn't work. (It worked on my Das-Kit Controller)
So I ordered a triple pole, double throw ON/OFF/ON switch with a waterproof rubber cover.
Hopefully it will be here by spring.

 

[6zfshdb]

Glad you got it working!

Apparently, There is a lot of variation in how the throttle circuits work on different controllers.

The circuit you show still acts as a voltage divider, even without the second fixed resistor. I'm not surprised that it works.

BTW, if you have a supply issue with those miniature TPDT switches, I have several spares with the waterproof cap. You're welcome to one at no cost. PM me if you're interested.

 

[PCeBiker]

Glad you got it working!

Apparently, There is a lot of variation in how the throttle circuits work on different controllers.

The circuit you show still acts as a voltage divider, even without the second fixed resistor. I'm not surprised that it works.

I could add a second resistor and increase the value of the first resistor to get rid of the dead spots in the rotation of the potentiometer, but the key component in the circuit is the 1K ohm potentiometer.

I'm pretty sure that is the standard for all throttles regardless of values of the resistors or whether or not full throttle is maximum or minimum throttle voltage.

I'm almost positive that anyone can use the power supplied by the controller to operate the circuit, so the separate power supply (3 button batteries) aren't needed.

I chose the ON/OFF/ON switch as opposed to the ON/ON switch to make sure that the two circuits aren't connected together while switching to prevent a throttle fault.
(Our electronics teacher called the ON/ON switch a "Make before Break" switch where the two circuit are connected together in parallel before turning off either circuit.)

BTW, if you have a supply issue with those miniature TPDT switches, I have several spares with the waterproof cap. You're welcome to one at no cost. PM me if you're interested.

The switch is on its way but it might take until the end of February to get here, but that's fine.
I'm not riding the ebike again until spring so I've got plenty of time.

I just ordered a 3 pin julet extension cable to wire in the circuit and help keep things looking clean.

I don't want to use coat hangers and duct tape for the install.

 

[PCeBiker]

When we bought the bikes, I somehow had it in my head that the throttles were just on-off. Blew right through the narrow progressive band without noticing for 10 months. Duh.

I had my ebike for a few weeks before I noticed the progressive band, and that band has about 3mm of movement.

This is my original throttle.
They describe it as a "quick throttle" because it quickly goes from 0-100%

Throttle off,..

Full throttle,..

The throttle is useless as a progressive throttle.
It's almost impossible to hold the throttle steady even when riding on a smooth surface, and it's really straining on my thumb trying to hold it still, so swapping out that throttle to something more effective was one of the first thing that I did with my e-bike.

Then I became a throttle hoarder.

I've got almost a dozen throttles now.

 

[PCeBiker]

It's Working In Tandem Now !!!

I just needed to add the second resistor.
I don't know the resistance value yet, but I have it dialed up on the 5K ohm varistor.

So now I don't need the TPDT switch.
I could cancel the order, but it was only six bucks, and I've always wanted a TPDT switch.



This is going to work really now.

I am really happy with my homemade "cruise control" and KT controller and display except for one thing.
There is still a split second time delay from when you first hit the throttle.

When I am riding Really Slow, (like 1 or 2 mph) right at the fall over point, I have to plan ahead and hit the throttle before I need it to keep me from falling over.

I did notice that if my throttle was activated, but just barely, I could hit the throttle and the power was instant.
So I would twist my cruise control just until the throttle activated then hit the throttle when I needed a bump.

But it was too hard to get my thumb in between the shifter lever and throttle lever, so I was going to glue an extension on the throttle lever so it would stick out further than the shifter lever and wouldn't be in the way.

But now, I can just install my thumb throttle normally and tighten it up, then when I am riding slow on the dirt trails, I can just turn my cruise control dial just enough to activate the throttle so my thumb throttle is always active and there will be no time delay.

My display shows me when the throttle is on and if I have a brake on it won't go until I release the brake.

The only problem I noticed with doing that is one time I had my twist throttle just barely engaged and when I released my brake, there wasn't enough power to rotate the wheel and I "stalled" it and got a throttle fault.

But all I had to do was rotate the throttle off then back on to reset it.
I didn't have to shut down and restart the e-bike.

 

[6zfshdb]

The throttle circuit design of any given controller will dictate how well a tandem throttle will function. In the case of the Dapu controllers I use, the results are erratic. Jumping from full throttle to nothing in unpredictable ways is the result I get. In my case, the TPDT switch is necessary for an either / or setting.

I suppose it would be convenient to be able to make a momentary speed adjustment with a twist throttle without turning a dial and losing the setting. The "fix" for me is the location of the switch. I have it mounted so it's easy to operate with the thumb of my left hand to switch between cruise, off or throttle. That way, I can get a quick burst of speed without losing the cruise speed setting.

I also like the switch to be able to turn the throttle system off completely without having to go through the display menu. It's too easy to bump, or have someone play with a twist throttle when I'm off the bike. I once had the bike fall over and go full throttle when the handlebar hit the ground. Luckily, the rear wheel was off the ground and the bike didn't move. I'm now in the habit of putting the switch in the off position whenever the bike isn't moving and before I take my hands off the brakes.

Family & friends also use the bikes. Until they are comfortable with the controls, I use a rubber boot to cover the switch with it in the off or throttle only position, to avoid accidents.

Lots of possibilities and personal preference here. YMMV

 

[PCeBiker]

Lots of possibilities and personal preference here. YMMV

Hmmm...

I do have another option where I could use the switch and glue a plastic tab onto the throttle housing to hold it at just barely on.

Then when I use the throttle it never shuts completely off so it won't have that annoying split second time delay.

If I switch on the throttle when the e-bike is already on, I won't get a throttle fault.

I like the simplicity of running both throttles at once with no switch or separate power supply, but a switch would probably be more fail safe with the switching options.

I've found that the only time I use the throttle normally is when I'm playing in the dirt and trying to do some hill climbing, but that's less than 2% of the time.

I could put the switch somewhere out of the way where it won't be hit by accident because I would only rarely be switching it to throttle.

I've got some time to think about it anyway.

 

[PCeBiker]

I got my cruise control circuit built and installed.
I started with the breadboard and increased the resistor values to 470 ohms each.
(I thought that I'd try to reduce the current supplied by the +5V from the controller.)


Then I tested for a ground fault.
(Someone mentioned that the ground wire fell off their throttle, and it went to full throttle.)

When I disconnected the ground from either the thumb throttle or the cruise control it went to full throttle.

I put the 330 ohm resistor back on the ground wire, then I got a "throttle fault" instead of full throttle.
(The signal voltage went over the 4.2 volt maximum throttle input voltage.)

I went to remove my button pad from my handlebars and the damn plastic clamp snapped.
I really like my KT controller/display, but they use crappy plastic.
It dissolves with acetone.


I Jerry rigged my bracket from my handlebar mounted reflector and attached everything to it.
(I've always called it Jerry rigged. Jerry's the guy that fixes stuff that can't be fixed. Nothing to do with a court case.)

I spent ~4 hours trying to fix the handlebar clamp.
It's wired directly into the display and isn't replaceable.
I used wire, zip ties, and some VHB tape that just arrived. (That tape is Awesome !!)

I soldered the two resistors directly to the potentiometer inside the housing.

I had removed a set screw to get the blue screw clamp out, and used the hole to put in a wooden dowel.
I zip tied the wire cable to the dowel to help keep it from getting yanked out, then filled the whole cavity with silicone.

It's Working GREAT !!!
It's really Ergonomic.
I can easily rotate the dial with the edge of my thumb.
There's a bit of a ledge above the dial to help me locate the down button by feel. That should help my muscles memorize everything.

The dial rotates from zero to ~2½ before the throttle kicks in then hits full throttle at ~7½ and the dial stops rotating at 8½.

I can easily set the dial to less than 1 Watt (my Watt meter reads zero), and my wheel takes 8 seconds to rotate once.

 

[PCeBiker]

Of course I forgot to put the damn shrink tube on the wires before soldering the connections.

I do that every time I use shrink tube.
You'd think I'd learn.
I did that twice today, but I luckily realized it before soldering the second time.

I put a zip tie on the wire and over-molded part and left the nub sticking out to give me something to grab on.
Then I put the 4:1 shrink tube with glue over top of everything to help make it solid.
I cleaned everything with acetone first so the zip tie and glue should hold better.

My two switches arrived.
I don't need them now, but they'll come in handy for some other projects.

I bought more "supplies" to have on hand in case I want to make another cruise control or fix the one I have.

The bracket for the reflector is perfect for mounting stuff close to the handlebar and at the right angle to attach things above or below the handlebars.
It's made with ABS or Nylon which is much more durable.
You can snug it up just enough to move it by hand but won't vibrate loose.
It uses a threaded wood type screw that threads directly into the plastic so it works like locktite.
No nuts to fall out and get lost.

You can open the clamp part far enough to get it over the handlebar, so you don't have to pull your handlebar grips and brake levers off to install them.

 

[6zfshdb]

Of course I forgot to put the damn shrink tube on the wires before soldering the connections.

I do that every time I use shrink tube.
You'd think I'd learn.
I did that twice today, but I luckily realized it before soldering the second time.

View attachment 169332

I put a zip tie on the wire and over-molded part and left the nub sticking out to give me something to grab on.
Then I put the 4:1 shrink tube with glue over top of everything to help make it solid.
I cleaned everything with acetone first so the zip tie and glue should hold better.

View attachment 169333


My two switches arrived.
I don't need them now, but they'll come in handy for some other projects.

View attachment 169335


I bought more "supplies" to have on hand in case I want to make another cruise control or fix the one I have.

View attachment 169338View attachment 169339


The bracket for the reflector is perfect for mounting stuff close to the handlebar and at the right angle to attach things above or below the handlebars.
It's made with ABS or Nylon which is much more durable.
You can snug it up just enough to move it by hand but won't vibrate loose.
It uses a threaded wood type screw that threads directly into the plastic so it works like locktite.
No nuts to fall out and get lost.

You can open the clamp part far enough to get it over the handlebar, so you don't have to pull your handlebar grips and brake levers off to install them.

View attachment 169340

Nice build!

Just one small comment I have. I noticed the 470 ohm resistor you used on your breadboard has a 10% tolerance (gold band). If it's the same one you used in your build, you might consider swapping it for a 1% (brown band).

Using 1% tolerance resistors in my project made a noticeable difference in stability & consistency. With the resistors mounted on the handlebars, they are subject to rapid temperature changes from sun and wind, which can affect performance. Due to their smaller size, this is especially true if 1/4 watt resistors are used.

My resistor values are much higher though. In your circuit, it's hard to tell if the resistor tolerance will make that much difference. Just something to keep in mind.

 

[PCeBiker]

Nice build!

Thanks.

Just one small comment I have. I noticed the 470 ohm resistor you used on your breadboard has a 10% tolerance (gold band). If it's the same one you used in your build, you might consider swapping it for a 1% (brown band).

Yes, both resistors (330 ohm & 470 ohm) are gold band.

Using 1% tolerance resistors in my project made a noticeable difference in stability & consistency. With the resistors mounted on the handlebars, they are subject to rapid temperature changes from sun and wind, which can affect performance. Due to their smaller size, this is especially true if 1/4 watt resistors are used.

My resistor values are much higher though. In your circuit, it's hard to tell if the resistor tolerance will make that much difference. Just something to keep in mind.

I'm pretty sure that it won't make very much difference.
I had the circuit working without the 470 ohm resistor at all.

I only added the 470 ohm resistor (and increased the 330 ohm to 470) to try and reduce the current flow when the potentiometer was at zero.

It only appears to affect the amount of dead spot before the throttle engages, and after the throttle reaches maximum.

When I started with the 2.2 k ohm resistors, the starting signal voltage was over the 0.8 volt threshold at minimum, (so I got a throttle fault) and well under the 4.2 volts at maximum for full throttle.

When I swapped the 330 ohm resistor for the 470 ohm, I didn't get a throttle fault if the ground wire falls off, and it went to full throttle (signal voltage below 4.2 volts) so I switched it back to a 330 ohm.


I found this similar schematic on endless sphere where they use 1 kohm resistors, but that still didn't work properly for me.

I did notice that my controller wasn't supplying a full 5 volts.
It was something like 4.35 volts, so getting my cruise control to register a throttle fault (instead of full throttle) only gave me about 0.15 volts of headroom and I needed to use the 330 ohm resistor.

So now my cruise control dial is actually safer than my throttle (and I'm pretty sure Any throttle) because it won't got to max throttle if the ground wire falls off.