Digital Potentiometer Control 

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Glad it was helpful!

Happy to help!

You're welcome!

Digipots are designed for small signal control applications not high wattage circuits. Check the data sheet for the wiper current spec ( IW ). It will vary with the pot resistance. ( A few mA ) You could buffer the output with a power op amp or emitter follower transistor/mosfet. I have used digipots in place of the control resistor in a LM317 voltage regulator circuit. www.onsemi.com/pub_link/Collateral/AND8414-D.PDF

Welcome!

You're welcome.

Yes .. as per data sheet specs the wiper can only handle a few mA. The digi-pot can only be used for small signal control but acts like a standard pot which people are familiar with so I used it for comparison. To control larger loads check out this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7sMU7vzpo3Y.html

The digital pot wiper will move as fast as you clock it. The maximum voltage you can apply to the digital pot is 5 volts. There are other ones that can handle higher voltages. Greater than the supply voltage. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-aHRnAT7PgGY.html

I do not use the Arduino IDE but program in Forth which is close to assembler.

silly question but why do you use Forth, is that just a comfy thing from previous experiences ?

You can use it anywhere a mechanical pot is used but watch the max current allowed specification.

The X9C103 contains 99 resistors with 100 wiper taps. Starting from the bottom ( 0 ohms ) each pulse on pin 1 will add 100 ohms of resistance. By counting the number of pulses you can adjust the pot to the desired resistance.

Check the data sheets of vendors that make digital potentiometers and note the maximum voltage and current spec of the resistor string and wiper. Ensure that your circuit is within these specs.

The X9C103 contains 99 resistors with 100 wiper taps. Starting from the bottom ( 0 ohms ) each pulse on pin 1 will add 100 ohms of resistance. By counting the number of pulses you can adjust the pot to the desired resistance. Pressing 2 on a keypad would pulse pin1 20 times resulting in 2k ohms.

Digi-pots are for small signal applications. To control heavier loads you need to buffer the Digi-pot output. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7sMU7vzpo3Y.html

Controlling high current to a load a PWM circuit using a MOSFET would be a better route to go. Check out this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-mjIubJeTRyY.html

Nope

Yes, this can be used as a volume control. The input signal to the amplifier will range from 0 to full signal level just like a mechanical pot.

Thanks for your reply. My plan is to have two input signals (L/R) and split it up to 6 output signals (L/R x 3). Then I want digitally control the 6 outputs, with 6 digital pots. Do you think that would be a problem when i split the two inputs into 6 outputs?

That can be done. Buffer all your outputs from the source signal. electronicsarea.com/1-input-4-outputs-stereo-audio-splitter/

Thanks, that could be a solution! I only have a +36 VDC supply through. I'm not an electronic expert :)

You're welcome!

It was a square wave oscillator but a sine wave would also work.

will sine wave swinging from +ve voltage to -ve work ??(not from 0 to some +ve voltage )

Yes .. the chip can handle +/- 5 volt signals with respect to ground.

ok i just wanted to use it as a digital signal attenuator to reduce the voltage of a sine wave signal using voltage divider method . but what about noise , will there be any addition of noise ??

The results will be the same as a regular mechanical pot.

Audio is applied to pot across RH and RL. Input signal is connected to RH and RL is connected to ground. Output audio is taken from wiper (pin5) and ground just like a mechanical pot. Normal op amps can not drive an 8 ohm speaker. I used the LM386 as my amplifier. Check out this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zMmaFV_JRAw.html

thanks for replying

Circuit diagrams at 3:27

Thanx

If the INC pin is held HIGH while the CS pin goes HIGH the wiper position will be saved. A digital pot controlled by I2C bus has a save mode that can be configured during programming. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-aHRnAT7PgGY.html

@@0033mer this seems a bit confusing. What I am trying to do is create a volume controller with two push buttons. One to go up and the other to go down. And it should save the value once I stop pressing either of the buttons.

INC will move the wiper up or down with push-buttons and stay. If not check the data sheet and your circuit. Make sure your push-buttons are de-bounced. The last post was referring to saving the wiper value on power down.

@@0033mer i think I found an alternative chip online. The DS1809-010+. It has an auto save feature that saves the current resistor value in its eeprom when it detects the Vcc shutting off. Then reads it on start up. And it only requires 2 pushbuttons for up and down so I won't need to use a microcontroller.

I do not use the Arduino IDE but program in Forth which is close to Assembler. If there is enough interest I will post some tutorials.

Check out this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zMmaFV_JRAw.html

The program was written in Forth. I do not use the Arduino IDE. : SET.LEVEL INIT INIT.X9C103 BEGIN Key dup 56 = \ STEP up IF STEP.UP THEN dup 50 = \ STEP down IF STEP.DOWN THEN dup 57 = \ JUMP up IF JUMP.UP THEN dup 51 = \ JUMP down IF JUMP.DOWN THEN dup 55 = \ Home IF WIPER.TOP THEN dup 49 = \ End IF WIPER.BOTTOM THEN 27 = \ ESC UNTIL PIN8 HIGH 10 MS PIN10 HIGH PIN13 LOW ;

A potentiometer wired as a two terminal device (wiper to outer terminal) is a rheostat as shown at 1:47. en.wikipedia.org/wiki/Potentiometer

My code in written in Forth but if you check the comments there is Arduino code available on Github : PULSE.INC Pin8 LOW \ Step wiper Pin8 HIGH ; : WIPER.UP Pin9 HIGH ; \ Set wiper direction UP : WIPER.DOWN Pin9 LOW ; \ Set wiper direction DOWN : STEP.UP WIPER.UP PULSE.INC ; \ Move wiper one step UP : STEP.DOWN WIPER.DOWN PULSE.INC ; \ Move wiper one step DOWN : JUMP.UP WIPER.UP 9 FOR PULSE.INC NEXT ; \ Jmp UP 10 steps : JUMP.DOWN WIPER.DOWN 9 FOR PULSE.INC NEXT ; \ Jmp DOWN 10 steps : WIPER.TOP WIPER.UP 99 FOR PULSE.INC NEXT ; \ Wiper --> TOP : WIPER.BOTTOM WIPER.DOWN 99 FOR PULSE.INC NEXT ; \ Wiper --> BOTTOM

@@0033mer I'm sorry to ask such a stupid question but where on github can i find this? I've just looked. I am new, just been trying to play with arduino and digipot MCP41010 for 2days now and cant seem to understand how to adapt a program to take button inputs to change resistance rather than just cycle through the ladder. thanks

Check out these sites: github.com/sleemanj/MCP41_Simple henrysbench.capnfatz.com/henrys-bench/arduino-output-devices/mcp41010-digital-potentiometer-arduino-user-manual/

Code is simply setting a GPIO pin high then low which a beginner to coding would know how to do. Samples of doing this is repeated many times in other videos.

@@0033mer You have taken it for granted that everyone Knows what a GPIO pin is - As I said Half a video. P.S Thank you for the reply.