How to stop a hall throttle at rest putting out 0.8v?

[AZguy]

Here's some links to some of those opamps, in DIP (easy to solder to) and in stock - cheap ($0.66), but you'll eat it in shipping so might try and stock up on other things

https://www.digikey.com/en/products/detail/microchip-technology/MCP6041-E-P/1098525

https://www.mouser.com/ProductDetail/Microchip-Technology/MCP6041-E-P?qs=g6BBfX6YTklKRtHW3RxJNw%3D%3D

I've got some customers up sort of towards 51 & Shea (closer to 101 and 51) but I'm sort of in a different corner of the valley and customer visits have dropped to near zero these days - I'm closer to 101 and 60... My work shop (lots of good electronics and bike tools LOL) is out this way too and right on the multi-use trail system for lots of riding, come visit...

[jrm7997]

I might just do that next time we are down there.

So i hope you guys are all doing well. My brother in law (phoenix) got his covid shot a couple weeks ago so he is very happy. Up here at the same age I'm not expecting it until June. :( Our numbers are over 800 new cases today which is VERY high for our area. Definitely keeping me away from shops and .............

In any case, I've attached a video (ignore the rattle its the Pot bouncing against wood) and a picture of the op amps I have been able to get my hands on. BTW, thanks for the links but i decided to try what I could get my hands on without going out and without paying a shipping cost. Yet. And I have another question. :)

First the video. Its pretty self explanatory. Left wheel Hall throttle right wheel 50K pot throttle. The two new motor controllers came in the other day so I wired it up last night and thought I'd show you how it works. Full speed without a load they draw 1 amp and i did try to stop the left wheel to see if I even need to worry about the 0.85 volts but I couldn't get near to slowing it down.

Video link

https://drive.google.com/file/d/1hgr1_U2i4Ugec3lZN3zmzL1iF7ZZoc-0/view?usp=drive_web

As for the op amps and 0.85 residual voltage. The picture is of the op amps I tried. Which brings up a question. I believe the TL081CP worked. 0.85 in and output was 0.1 but when i increased the input voltage to imitate the hall throttle the output stayed at 0.1 volts. It would need to increase to signal the motor to go faster. Is it the op amp or theory? So if the voltage should have increased i definitely will order the proper op amps in. I think those thumb throttles are the best way to go and each one has a built in switch so I'd end up with the two switches i need for reverse and on/off

Picture link

https://drive.google.com/file/d/1VdHbjW1p-YEIDbGxZk09mArK5_r-SkEl/view?usp=drive_web

Thanks
Jim

[jrm7997]

I was going to mention something else. How to get lost inside a computer? Go to digi-key and try to figure out the parts. :) I started by adding 6 of the op amps then checked out the shipping. $11 cdn. So then I went back to look up some trim pots. Talk about toooooo much information. I ended up going to the Lees electronics site and used it to figure out the part names then I went back to search digi-key site. I found that Lees has much better pricing and they are local. But they don't have the op amps you suggested. It became worse when i tried to find jumper cables/sets, crimps, sockets etc.

I guess it wouldn't be too bad if you knew who made what or proper names for things. I've just been out of it for so long that i think its time for a martini or one of the beers i found while on my walk. Cant believe I've been walking and riding past a micro-brewer for at least 10 years and just found out about it today. Funny part is that when i mentioned that to them the guy laughed and said they had only just put the sign up a few weeks ago.

[AZguy]

The TL081's won't work - you need something with more input and output voltage range, those are very limited... I'd look for something with rail-to-rail input and output to be safe

I can't open the links, it needs a login

Yeah down here I got my first shot a couple of weeks ago and getting my last one next week - be glad to put that in the rear-view mirror (I'm 60)...

[jrm7997]

Well i just ordered the 6041 from Digi pen.

I was going to start making hte PCB and wondered what program you use for laying them out? Once i print them I can get then etched at a local school.

[AZguy]

I use several, all expensive though, it's part of my business... Altium, OrCAD, Eagle, etc.

There's a free open source one that one of my customers was using called KiCad that I loaded long enough to work with their files but can't really comment on how well it works

[jrm7997]

TADA :) Success. Thank you AZguy.

I received the right ICs a week or so ago and had it all breadboarded ready for a day like today. I have the PCB layout completed and a friend is going to etch them for me. As for software, I used Dip Trace. It worked fine with a fairly short learning curve.

Right now I have it setup to use the built in switch that is part of the thumb controller to turn both BLDC motors off. My next step is to figure out how to use the other thumb controllers switch to reverse both motors. Funny thing is, that when the motors start up they both turn CCW. Sounds fine until you realize it will make the Tug spin in a circle. One needs to be going CCW and the other CW to make the Tug go in a straight line and not spin in a circle. :)

So I have to create the condition where one motor starts up normally and the other is signaled (neg to Rev pin) to be in reverse. When i want to go the other direction the thumb switch can operate the one motor normally and I'll have to use a relay on the other to disconnect the negative to the reverse pin.

Looks like I better call my friend and tell him to wait on the PCBs until i can find a relay and do some more schematic and PCB design work.

Thanks again for all the help.

Schematic attached

[AZguy]

Very glad that's working well for you - enjoy cranking those out

Would recommend small ceramic capacitor (0.1µF or 1µF / 10V or more / X7R) across the opamp supply pins (4 and 7 on your schematic) this will help ensure it doesn't oscillate and reduce the noise on the output

[Tommycat]

Well done on the throttle mod lads. Your schematic docx only shows a section of the total schematic... do you have a full view available?

It might be an advantage for you to reverse the one motor's direction by changing it's wiring, verses using the reversing function of the controller.

At the end of the flow chart below you will see what is required. I.E. - On a hall sensored BLDC motor a swap of phase wires, as well as a set of hall sensor wires are required. Typically of different color combinations.

This would allow you to use the same switch for both reverse functions, if both controllers are using the same power supply.

[jrm7997]

I'm feeling kind of blond right now :). Or, to be politically correct (based on a class of grade 8s calling me on using he blond term) i feeling very Torontonian ( us westerners love to hate Toronto) . I forgot about switching the wires for proper operation and direction. I did that a while back and have it running. Thanks I'll play with it and get the one motor running in the right direction.

The full schematic is on post number 1.

Ill let you know

[jrm7997]

Good morning. (At least where I am)

I finished off the electronics last night. Prototype #1 is working thanks to you guys and I greatly appreciate the help. I didn’t add videos because I can’t so two pictures will have to do. The boards upside down in the pictures. The sheet of plywood on the bottom will be for mounting the batteries and handle.

using AZguys circuit my buddy cut the PCBs (BTW I used Diptrace to create the pub layout) for me and I received them a couple days ago. So now that they are connected I have two thumb controllers with one of the controller buttons for on/off and the other for F/R and no wheel spin when the thumb control is at rest. :)

With that done I’m heading out to the airport later today to start the connection to the airplane. I’ll make something temporary until I find out if a hoverboard can push and pull the weight.

Thanks again for the help.

[AZguy]

Woohoo!

Awesome

[savroo]

Hi AZguy I found this diagram in another forum do you think this will work? On the second op-amp what does U1 mean??? Thanks in advance if you reply back.

regards

sav

[AZguy]

Hi AZguy I found this diagram in another forum do you think this will work? On the second op-amp what does U1 mean???

It looks pretty similar to the one I drew. The opamps in this one can pretty much be used interchangeably with the one I used in either circuit

U1 is what is called a reference designator. The TLC2272 is a dual op-amp (two op-amps in one package) so both the op-amps in that drawing are in one IC.

The circuit is very similar to what I did. Without chewing the numbers I can't say exactly what it will do but it looks pretty much the same except for the adjustment potentiometer and that it is scaled to go from 1 to 4V vs. 0.8 to 4.2V in the one I provided. When I worked the numbers on the circuit I provided I didn't really think an adjustment would be necessary so I left it out and frankly it doesn't need two op-amps but since they are in the same IC no big deal IMO...

[savroo]

AZguy thank you very much it worked and the results.

https://youtu.be/kvPZxuPadxk

see last bit of the video for the components.

[savroo]

For everyone that has come to this webpage, you can see above op amps used to convert a Hall effect to give 0 to 5v reading instead of 0.8 to 4.2v approx. I’ve been using the above diagram but my son’s car is ready for more battery voltage. I revisited the op amps it was always difficult to calibrate with the pot and was abit sluggish to get to exactly 0v when you let go of the throttle. This is me being thick but the first op amp in the wiring diagram does not show the powered wires to power one of the op amps pins 4 and 8. I think I built at least 3 circuits with new op amps this week as just couldn’t get them to work perfectly I’m thinking I have blown the op amps. Anyway I just gave it a go and wired the op amp in the diagram with power pins 4 and 8. It now works perfectly, is not sluggish and easy to calibrate. I’ve added the wiring diagram to exactly show how to wire up.

This is someone who can solder but has got minimum experience of electrical engineering, so was just following the wiring diagram. See diagram and when I need to build another one will come back to this page :-)

[AZguy]

The TLC2272 is a dual op-amp (i.e. there are two devices in one package) so only one set of power pins for two devices that are in one package

[jlh]

Reaching out to AZGUY.
I am tuning my grandson's electric Gator and was looking for a way to substitute the pot for throttle/speed control with a hall effect throttle. I'm using a very basic PWM controller with no soft start or ramp up time. First I found the quad op amp design that I presented here then Savroo's dual design and then your design.
I don't grasp the quad design as to why the additional 2 op amps.
If you could expand on the why and pro's / con's of the 3 versions I would enjoy the education.
I enjoy browsing the posts and enjoy seeing all the talent that is gathered.
Regards

[AZguy]

That LT part is overkill for sure (very expensive!), but doesn't really matter

The three are just all connected with outputs more or less in parallel to the "master" which would ease how much current each one delivers but the 200Ω resistors on the outputs will limit that current anyway and keeps the amps from "fighting" with each other and if they're there might as well use them I suppose - definitely don't want to leave their inputs unconnected regardless. It might make sense if they were expecting driving a lot of capacitance but I wouldn't expect that...


I guess I lean to the single op-amp solution I put forward based on the cheapie MCP6041, but then again it's mine so I'm not unbiased LOL. It does lack the adjustments although they'd be easy enough to include, they just don't seem necessary with a decent opamp... Two (or more) op-amps don't help anything here, just a different approach.

It's a lot cheaper - the MCP6041 is less than $1 and the LT633 is >$14(wow!) and even the TLC2272 is >$2.50... it's very available too (in DIP - much easier to solder too), not so much the LT

Plus, a fellow built it and tried it so it's a know good, at least in his application. I wouldn't bother with trimpots but then again I've got a decent selection of resistors and could fine tune them if need be but my dim recollection is I designed it taking into account tolerances, etc. to ensure it would goo all the way to 0V and 5V without any significant dead play.

And not that it makes much difference, but I gravitate towards "elegance" and simplicity and there's something appealing to the eye about jut one amp, and only four resistors and only two values... but that's just "pretty" and doesn't have anything to do with functionality...