How to wire a SPDT On-Off-On switch

[NeilP]

I am sure we all know the standard On-off-on switches that we often use as a three speed switch on a Infineon controller.

But how would one wire one to give a 3 position LOW- MED-HIGH current limit on a Cycle Analyst

I know it is a matter of switching voltage to the Vi pad as per the manual and the below diagram, but I just cant work out how to do it to get L-M-H with this standard SPDT switch.

I have plenty of these switches on the handle bar mounts, but can't work out a way to do it.

I know it is only a matter of switching resistors, but i can't see how to wire it up.






related question..anyone know what range of current is deemed safe to take from the 5 volt pad for the divider network...a couple of mA max? less? more?

 

[wesnewell]

You can't get 3 positions from a spdt on off on switch. You can get a default with center off and 2 separate positions. You need an on on on switch to get 3 different outputs. Check your local electronics store. Like these.
http://www.ebay.com/itm/Pack-of-5-On-On-On-Toggle-Switch-6-Amp-M2033-5-/190816103462

 

[NeilP]

Umm not strictly true..you can, but it ends up as Low- High- Medium Not Low- Medium-High.

You use the switch to parallel two different resistors across one half of the bridge, so you have resistor one across lower half, no resistors across lower half or second resistor across lower half, giving three values at the centre tap. But it is nto in the correct 'order'

I was convinced there is a way to do it, but just can't get my head around it. Even if it involved using a transistor or two somewhere. Just so I can use the ready made handle bar switch and its mount without having to create and waterproof a new switch on the handle bar

 

[NeilP]

the alternative is to find a DPDT switch as you ling to in the same form factor as the rocker switch I already have..the little black ones that come with many of the kits for three speed.

like these, but smaller..they look to big...

http://www.ebay.com/itm/30-Amp-DPDT-On-Off-On-Rocker-Switch-/150306592041?pt=LH_DefaultDomain_0&hash=item22fef89529


Easier I know, but I wanted to try using what I had to hand...creating difficulty to be cheap :wink:

maybe this is the correct size

http://www.ebay.com/itm/5Pcs-Plug-in-On-Off-Rocker-DPDT-Switch-6-Pin-12V-110V-250V-6A-10A-/370633211288?pt=Motors_Car_Truck_Parts_Accessories&hash=item564b75fd98&vxp=mtr

 

[wesnewell]

If all you want is a 3 speed switch for an infineon controller, all you need is a spdt center off switch. You don't need a sptt on on on switch. If however, you actually need to send a signal to 3 different locations, you do. Simple as that. Been there, done that, many years ago. I've got several of these switches laying around. I've used hundreds of them.

 

[NeilP]

No, don't need a three speed switch, already got one of those..I too have many of them lying around.

I want to wire the Cycle Analyst for three different current limits, but leave the speed settings the same, the three speed switch on the other side of the bar, by the throttle, a curent switch ont he LHS

If you go back to my first post , you will see the diagram from the CA Manual. The CA has three pads that you use ...a 5 volt feed, a ground and the Vi input pad.

You set the Aux voltage setting in the CA menu to Current limit, and then feed a voltage to the Vi pad. It can be done via a pot or as many switched resistors as you want settings to give various current limits, up to the max set in the controller.

There are many many ways to achieve this, but I wanted to do it with the hardware I had to hand, namely a 3 pin SPDT on-off-on switch.
It can be done to give the three current limits, but the switch would give it as Low- High - Medium




Usable but not as logical as Low- Medium - High.

I was just trying to get my head around if there was a way to wire this switch in this scenario, to give it in the conventional order LMH

That give Vi as
Low...1.18 volts
High... 3.26 volts..so max current limit ( 3 volt gives max as set in CA menu)
Medium... 2.25 volts

 

[ddk]

as you pointed out, the simplest approach would be a dpdt center-off switch but you don't happen to have one of those laying about.
A spdt center off can be used by building a simple truth table converter using a couple of quad nand gates and a couple of resistors, if you happen to those laying about instead ... or one quad nand and a quad inverter
If you like puzzles I'll let you puzzle it out
if not ask, and I'll draw it out for you

or buy the dpdt switch :lol:

 

[NeilP]

Would be interested to see that solution..not that I will have those parts lying about either..I know this is OTT for the need but interested none the less

 

[ddk]

-didn't get too concerned about labels cause I'm a lazy sob

 

[ddk]

-didn't get too concerned about labels cause I'm a lazy sob

this is wrong but it's bed time for bonzo
I'll fix it after I wake up
but that's the concept...

 

[NeilP]

I get the idea now, interesting..more to learn

Cheers

 

[wesnewell]

Must be engineers. Making something so simple so complicated and using more parts than needed.

 

[NeilP]

Exactly..why over simplify things ??

 

[ddk]

Exactly..why over simplify things ??

a couple of cheap chips on a small piece of perf... a few minutes soldering time.
however it helps to know how to apply gates (circuit PS bypassing et al)

otherwise use a dpdt switch
be having a nice day pleez

 

[NeilP]

have looked throught my parts bins, no chips like that kicking around, so guess it will have to either be a DPDT or put up with LHM rather than LMH ..its a hard life :wink:

 

[NeilP]

You can't get 3 positions from a spdt on off on switch.

yes you can..found it...I knew there had to be an way. Just found this from teklektic on the CA V3 thread

R1 = 10K, R2 = 4.7K, R3 = 4.7K

http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=37964&start=1553

 

[NeilP]

Just putting this here while at work..

 

[teklektik]

Neil-
You are right - there are several ways to accomplish the SPDT solution that you wish. The CA V3 resistor divider that you are using will certainly do the job, but there is a bit of a twist for use with the V2: the V3 has an adjustable input range (both min and max voltages in the range 0-5v) but the V2 has a fixed voltage range of 3.0volts with an adjustable minimum in the range 0-5v. This was done to support 'current throttle' hookups with hall throttles that typically have a 3v output. Setup configures the minimum via AuxThreshold - so if AuxThreshold is set to:

• 0v, then the input range is (0v) to (0v+3v=3v) or
• 2v, then the input range is (2v) to (2v+3v=5v)

So - you just need to diddle the resistors slightly differently than you might with the V3. But - you can work the same trick with adjusting the effective LMH limiting percentages with the V2 that is described here for the V3, except you only have independent control over the minimum input voltage. I took the liberty of adding to your posted XLS file above to calculate a table of LMH percentages and actual Amp limiting for a variety of Aux Threshold settings - your basic calculations are unchanged (just moved to different cells ).

Here's a shot of a sample resistor set that has been selected as an example to give (LMH) = (34%, 66%,100%) with Aux Threshold set to 1.0v. This allows you to jiggle the effective limit values a bit through Setup by simply adjusting Aux Threshold up or down.


Here's the XLS - unprotect the sheet to tinker the yellow cell calculations.
View attachment LMH Switch resistor calc 2.xls

 

[NeilP]

I did build up the switch in the LHM setup a few months ago, initially using pots as a test, then when I had the pots as i wanted I I found resistors to suit and give a similar set and as you say, jiggle the lower setting with the Aux threshold. it was setup such that the High position always kept 100%.

That spread sheet I did was made up in a internet cafe a few days ago, and posted it on the thread, as a storage method, just to get an idea of what values, I was going to need. Nice work with the addition of the current limit section.

I was aiming for a split of around 15 45 and 90 on my setup, which I did achieve happily but the switch being LHM (and not LMH,) but it does occasionally give me a hell of a shock followed by realisation, when I flick from low to medium..but suddenly find myself in high!

 

[teklektik]

I was aiming for a split of around 15 45 and 90 on my setup, which I did achieve happily but the switch being LHM (and not LMH,) but it does occasionally give me a hell of a shock followed by realisation, when I flick from low to medium..but suddenly find myself in high!

I actually use an LHM switch because I use a toggle and the High setting is boost mode - I'm usually in Low or Med. With a toggle the LHM configuration makes it easy to just sweep the toggle to either extreme to get the 'usual' settings - a little more care is needed to get to the center boost mode. The LMH configuration is much more natural for a rocker switch.

Anyhow - you gotta love Excel for chugging out quick 'what ifs'