vikoma
Member
The objective was to replace the potentiometer in Lightspeed attenuator of Pass B1 project with remote controlled arduino.
I recently got SSP and was very pleased with its performance in my system (Rasp Pi -> Peachtree DAC ITx -> SSP -> Norge 1200 power amp). The only thing I missed was remote volume control. Though I had Pass B1 kit (which I have started rigging up only now), I missed Lightspeed attenuator. But even that also has only potentiometer based volume control.
So this is how I did Arduino based remote control:
I recently got SSP and was very pleased with its performance in my system (Rasp Pi -> Peachtree DAC ITx -> SSP -> Norge 1200 power amp). The only thing I missed was remote volume control. Though I had Pass B1 kit (which I have started rigging up only now), I missed Lightspeed attenuator. But even that also has only potentiometer based volume control.
So this is how I did Arduino based remote control:
- Get Arduino Uno R3 boards (Approx. Rs. 600).
- Also got a small IR board which receives IR signal and conditions it to be received as digital signal for arduino.
- Write a Arduino software (on your PC) to drive Arduino uno board:
- Use IR library, and to recognize the codes from any well recognized IR remote. You only need up/down codes, and then hardcode them.
- Maintain a level control - say 1 to 25 to track the volume level.
- Output a PWM signal on one of the analog-out's, corresponding to volume level. It ranges from 0-255; higher corresponds to full 5V output, and 128 to 2.5V. Technically it is a square wave with variable duty cycle.
The "analog" out is then connected to circuit shown. Basic idea is to use a transistor to drive a constant current circuit, which in turn drives LEDs.
I bought cheap LDRs (which cost Rs. 5/- each), and physically coupled them with LED light. You can see one of them with black wrapper. I am using heat shrink tube.
I am attaching a circuitry which is essentially same as Lightspeed attenuator. However our mentor FM omishra reviewed it and pointed out a problem: Shunt LEDs have to darken when Series LEDs brighten. For now, I will only use series LEDs and just use 1MOhm resistance as shunt. (I am totally new to the electronics; so will receive feedback and incorporate them.)
While it is not yet fully tested in live system, I tested the resistances available to us: It ranges from 50 ohms (when fully bright) to very high (>> 1MOhm) when dark. I am roughly getting about 10 steps of clearly identifiable LED brightness levels. I will change the software to smoothen/control the process later.
The cost is indeed quite low. Arduino uno R3 board is also available in nano version, costing only Rs. 300/- (without USB-to-serial interface) i.e. you can use in in final version and keep main arduino for other experimentations. Components cost shouldn't exceed Rs. 100/-.
Attaching pic of my build (I first did it on breadboard; and then on general purpose PCB), and circuit I am using. I will be sharing arduino software later. And perhaps write up a detailed step-by-step approach if you really want instructions for arduino in detail.