How to translate a large variable resistance to a low variable resistance

[Waynec42]

Hi,

I'm new to this forum so I hope this is the correct place for this question.

Having studied electronics a number of years ago, I'm not as knowledgeable as I would like to be in regards to analogue circuits, but I'm sure what I'm trying to do is possible.

Here's the question.

I'm a drummer. I play an electronic kit (2box brand). The foot pedal that simulates the hihat has a variable output of 700Ω to 800Ω. I would like to use a different brand of foot pedal (Roland) for this input. The problem being that the Roland foot pedal is 0Ω to 20kΩ as well as being reverse polarity - 20kΩ to 0Ω.

Can anyone recommend a simple circuit to translate a 20kΩ to 0Ω input to a 700Ω to 800Ω output.

Thanks.

 

[AMS012]

Hi,
Connecting a suitable resistance in parallel would make it.

 

[keith1200rs]

Hi,
Connecting a suitable resistance in parallel would make it.

Sorry, but it won't.

I am not aware of a simple circuit to do what you want. You could check the DIY section of the Vdrum forum if you haven't already done so.

https://www.vdrums.com/forum/forumdisplay.php?48-DIY

Keith

 

[AMS012]

Hi,
I think this will work. Pls follow the link
https://obrazki.elektroda.pl/1964705400_1353850533.png

 

[keith1200rs]

That will turn a high resistance into a low one but the problem requires the opposite. Also, it won't reverse the direction of travel.

It may be possible to use a simple transistor circuit where the pedal progressively turns on a transistor with an open collector/drain with a series resistor added. Most modules simply have a pullup resistor (to 5V) internally - maybe you could measure yours?

My main concern would be how progressive it could be. I could look tomorrow to see what might work. My main experience is with Yamaha modules.

Keith

 

[Waynec42]

That will turn a high resistance into a low one but the problem requires the opposite. Also, it won't reverse the direction of travel.

It may be possible to use a simple transistor circuit where the pedal progressively turns on a transistor with an open collector/drain with a series resistor added. Most modules simply have a pullup resistor (to 5V) internally - maybe you could measure yours?

My main concern would be how progressive it could be. I could look tomorrow to see what might work. My main experience is with Yamaha modules.

Keith

Thanks for all the replies.

Unless I haven't explained myself correctly or I'm misreading it, I do need to change the high resistance into a low resistance. The other part is correct about reversing it.

I like the transistor idea. I'd have to re-learn it all but from what I remember about transistor theory, this sounds promising.

I look forward to further suggestions from people who know more than me.

- - - Updated - - -

Hi,
I think this will work. Pls follow the link
https://obrazki.elektroda.pl/1964705400_1353850533.png

Thanks for this, but I've actually tried this method. I found it works in theory but isn't linear enough. It goes from no change to a sudden maximum change. I can't remember which direction though.

Keep them coming though.

 

[keith1200rs]

Sorry, I misunderstood.

Do you actually have a Roland pedal? If not, the Yamaha pedal works (HH65 I think) the correct way round for you needs and although the resistance is very high it is set by fixed resistors on a PCB which are progressively shorted out so could easily be changed.

Keith

 

[Waynec42]

Sorry, I misunderstood.

Do you actually have a Roland pedal? If not, the Yamaha pedal works (HH65 I think) the correct way round for you needs and although the resistance is very high it is set by fixed resistors on a PCB which are progressively shorted out so could easily be changed.

Keith

Ok, thanks for the info. I don't have a Roland pedal, but I have access to one for testing purposes. I don't want to purchase one if I can't use it.
I'll look into the HH65. You wouldn't happen to have a circuit diagram for the HH65?
Cheers.

 

[keith1200rs]

Yes, see attached. The pedal works by having conductive rubber which progressively shorts out the resistors through pads on the PCB. You end up with a low resistance when the foot is pressed on the pedal, which I assume is what you want. The resistors are standard through hole, so easily changed. The ring connection is to do with the splash, I believe, as is the diode/capacitor. Roland modules don't use the connector ring - I don't know about the 2box.

I assume you have seen Jman's posts about hihats on the unofficial 2box forums?

Keith.

 

[Waynec42]

Yes, see attached. The pedal works by having conductive rubber which progressively shorts out the resistors through pads on the PCB. You end up with a low resistance when the foot is pressed on the pedal, which I assume is what you want. The resistors are standard through hole, so easily changed. The ring connection is to do with the splash, I believe, as is the diode/capacitor. Roland modules don't use the connector ring - I don't know about the 2box.

I assume you have seen Jman's posts about hihats on the unofficial 2box forums?

Keith.

Thanks for the pdf. I'll have another look at the 2box forums. There's a fair bit on there about hihat options.

 

[keith1200rs]

Actually it is Manfreds posts you maybe want to look at, not Jmans.

http://vdrums.com/forum/showthread.php?70926
http://www.2box-forum.com/index.php?topic=973.0

Keith.