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

[jrm7997]

Well I'm about to order the parts. Having a bitch of a time finding the op amp. One of the stores was closed the other wanted $5 for an equivalent and so on. Found out last night that the closed store got bought out and has moved. Just called and they can get MCP6041 in a couple weeks. I have one more option left but I've just been getting a busy signal.

Azguy i was rereading this and noticed the comment that you also fly and are in Arizona. Anywhere near Shea and Hwy 51? My brother in law in that area. We go down pretty regularly and one of my favorite areas to visit. :) what do yo ufly and out of where?

[AZguy]

The 082 (you meant TL082?) doesn't have rail-to-rail in or out - you pretty much need that for this application. You could do it with a rail-to-rail out only but it would require more resistors - trying to keep it simple

[jrm7997]

I forgot I was going to mention shipping (comment in your power supply post). Shipping to or within Canada is an absolute fricken joke. Canada post is great but the cost of shipping is ten times or more. I once shipped a center console from a 2004 Chevy truck to a guy in the south eastern USA. Shipping from Vancouver was going to be around $300. I shipped it from Point Roberts WA for less than $100.

What we usually find is that shipping is generally free within the USA. So i have my shipments go to a mail box in Point Roberts, drive across the border and bring it back. If its under $300 they don't usually charge taxes or duties. Unfortunately with Covid and the borders being closed I can't use Point Roberts. I even have some Honda CT90 parts sitting in Point Roberts since March last tear that i cant get too. :(

So a lot of my buying has been toned down a lot. Just waiting for this too end so I can start RVing and everything else.

[73Eldo]

That is a really cool power supply! I wonder why there were not more like that. Lots of features in one box for a general repair or tinker.

[jrm7997]

Sorry I've not replied. Its been too cold to work in the garage and I seem to have picked up a pretty wicked cold. Gotta tell you I'm wondering how I could have got a cold with all the washing, disinfecting, masking etc. But i'm glad I didn't have to do the nose swab Covid test. Been there done that and don't want to do it again. I got the gargle tests this time and came up negative. I got the test just in case. Just a cold :)

I have been following that tug thread. Its where I got the idea to keep my eyes out for a busted snow blower. If i can get this one to pull well enough I'll definitely be looking into that wheel grab. It looks pretty slick.

I looked up that power supply. That's not a bad deal with a lot of options. But I think i have myself covered for the little i do. I took a picture of the two power supply's i have. The one on the left works well, 30vdc and I think its good for 2 amps. The one on the right is a throw away I got back into working condition. Everything works and I love two things about it. First the isolated 110vac. Just a tad safer. Second you cant break it and it puts out 10 amps. Oh and third, if you have a dead car battery you can start your car with it :) Just kidding. They are build like a brick sh** house so keep it around.

I breadboarded the op amp you sent. Unfortunately I only had one op amp (T082acp) and a mish mash of 50K and 25K trim pots to put it together with. I did have two 22K resistors though. But i think with too many jumpers and places for errors it didn't work. Could also be the op amp i have :) Because I've been sick I have not gone out but will pick up the appropriate parts to try your cct with. Thanks BTW i appreciate it.

As for the hover board I got her all wired up a few days back and it didn't work. Worked on the bench but not after wiring the two controllers together. I didn't put much time into it because it was cold out there and my brain really couldn't get into it. Its going to start raining here in a day or so and should warm up. At least enough that the little electric heater can keep it warm enough.

So ill keep you updated.

[AZguy]

BTW, I'd put a small ceramic capacitor across +5V and ground very close to the opamp

[AZguy]

A local place carries some decent power supplies... easy for me since I can just drive the five miles to pick them up, shipping might kill the prices

I've got one of these for general purpose:

https://www.circuitspecialists.com/0-30V_0-5A_bench_power_supply_with_60_memories.html

I've got several others but that's a good one for the price, not quite as accurate as they say but both current and voltage are within a couple of digits worst case, most of the time within one digit... easy to adjust and enough voltages and current for 90+% of bench top stuff... has constant current so will charge batteries but you need another supply in series to get up to the bike battery voltages

[AZguy]

This gets you very close for 0.8 to 4.2 in

Resistors need to be tweaked for different input range

The MCP6041 opamp is available in DIP (easy to solder to or breadboard) for <$0.70... nice general purpose for up to 6V with rail-to-rail in and out

If you'd like the simulation I can provide

If I were going to put potentiometers for fine tuning I'd put a 5K in between R1 and R2 with the wiper going to the opamp and R3 and I'd put another in series with R3 (connect the wiper to one end)

[Tommycat]

Some inspiration as provided by the thread above...

The wheel "capture" mechanism is neat!

[Tommycat]

Found the Blackjacks, but it looks like their web site is down. Or bad link perhaps.

https://vansairforce.net/patches.htm

But most importantly, you have to check out this thread on VAF! Tons of great ideas and information from lads who have been there.( no D8s suggested, but I've seen mention of electric golf carts now and then that sounds interesting. :-)
Check out the joystick link for sure.

GO HERE NOW!


Thumb's up on the "off topics" LOL, sometimes I never get em....

[Tommycat]

Sharp looking tester. Variable output, snap on integration. But best of all, overload and short circuit protection! Found for <$50 U.S on Amazon...

AZguy, do you have a parts list so I can poke around and see what I have in my kit, or have to order...?

[AZguy]

No the resistors are not all the same - this was just the basic topology... 100 was for the emitter follower

Since you are interested I'll work them out, likely have them today, this one's easy

If you want it adjustable, in particular for the offset (but also the "gain") I'll add optional potentiometers

I can make sure all the parts are available at digi-key or mouser too... it'll be cheap

[jrm7997]

See my comment above about the breadboard power supply but i like your usb idea. I could work up here in the warmth instead of having to heat up the garage each time i go out there.

Good advice on testing before throttling :) and I wont know how much a voltage drop will affect its usability until I load it up with some weight. It might work fine or i might be into version #3 the full mobility chair. FYI, if that one fails I'm keeping my eyes out for a snow blower, lawn tractor or ????? D8 :)

Definitely a Vans fan but I bought I didn't build so i usually go there for the "off topic" comment on the bottom of the first page. Todays took me a second but i got it. For AZguy so you know what we are talking about go to the bottom of this page https://vansairforce.net/

No smoke. I gave that up 20 years ago. :)

[jrm7997]

That looks easy enough to breadboard. I have a good bench power supply that can do all this. BTW, while i think about this, a small company called evo-in-motion makes a very slick little breadboard power supply. https://www.eimtechnology.com/product-mego When i was teaching they gave me one as a sample.

Just to clarify a couple thigs. All the resistors above are 100 ohms? vin is base, vout is emitter and 5v is the collector? Thanks i just don't like the smell of blown transistors. :)

[Tommycat]

I like to use a small USB (5vdc) rechargeable back-up/charging battery that has a switch for bench testing. Get close and the bugs worked out using this first before using you controller regulated power which typically only produces <100mA.

Best results I've gotten so far is with a Darlington circuit using (2) PN2222 transistors with a 100K resistor between the base of the second transistor to batt negative. .07vdc closed @ 5.83mA and 3.41vdc WOT @ 5.76mA. With 5.1vdc supply input. Note: no resistance on output. But when I was previously testing for typical controller input resistance, I would use a 1K resistor on the output. It would drop my .85vdc unloaded sensor output to .8vdc, which is what my controller would pull it down too.

I fear that the magic of electronics comes at a slight voltage drop cost. So a boost in input voltage might be needed for full power output range? But perhaps good enough for testing at this time...?
Looking forward to AZguy's Opto circuit. I'm just a pure novice, but having fun learning. Sorry about the probable unnecessary warnings lol. But it took me just 2 hours to toast my new testing breadboard's power supply.

I was wondering if tug wheel traction would be an issue. Does your mission include portability, or perhaps lack of hanger space?





Thanks for the heads up on the formation groups... will look them up. Do I see a smoke mod in your future? ;-) I would speculate your a member of another great forum group, VAF!