One Shot IR Helper Is A Great Beginner Project

Sometimes you need a little utility device to do a very simple job, and do it well.This one-shot IR helper from [Gregory Sanders] is just that. 

[Gregory] had a TV that didn’t support automatically turning on when the power was applied. This is frustrating when you like to leave devices switched hard off when not in use to save on standby energy draw. Thus, there needed to be a way to send the screen an on signal when his multi-monitor setup was powered on.

A simple circuit paired with a Pi Pico was pressed into service. The Pico flashes an IR LED, squirting out the requisite code to tell the TCL branded TV to switch on. [Gregory] figured out the codes by using an Arduino to read the output of the TV’s remote with an IR sensor. The hook here is the code is written in MicroPython, using IR libraries from [Peter Hinch].

Now, when [Gregory] powers up his rig, the IR sender will trigger the TV to switch on. It’s a little frustrating that the auto-on function wasn’t available in the factory, but regardless, now everything’s working as it should. If you want to do this in reverse, consider building a TV-B-Gone or a silencer for the boomboxes used by dancing grandmas!

50 thoughts on “One Shot IR Helper Is A Great Beginner Project

    1. There’s really no room anymore for MIPS between ARM and RISC-V.

      I still think there’s room in some places for an 8-bit, but the space for that seems to be shrinking rapidly.

      1. Yeah it’s totally random individuals with small quantities for hobby use and not large companies hoarding piles of components either to use in the future production or to scalp at ridiculous prices …

  1. This was a job for an ATtiny. They should have connected directly to the IR receiver and made the whole thing entirely internal. Seriously, this doesn’t need to take more than 2KBs.

    1. Sure, but anything AVR based is far more expensive now than it was three years ago. Pi Picos can actually be had for their list price of $4 at a microcenter or online.

      I’m a huge fan of AVR, but nowadays it usually isn’t cheaper than a Pico. Also, if anyone else is like me, they have a couple Picos banging around that need to get used, and why not use it in a project like this?

        1. Absolutely! I’m just saying that this person isn’t automatically a fool simply because they used a 32-bit MCU instead of 8-bit.

          In learning the Pico for my current project, I’m realizing just how much I love AVR’s timers. I also somewhat prefer the UART bootloader to the Pico’s interesting copy-onto-drive thing (though I’m sure people have made second-stage UART bootloaders for it).

          Pros and cons to everything, including availability, price and toolchain.

    2. Absolutely my first thought, attiny85 , IR sender Led, driver, replicated remo-code, and then use the USB programmer port 5V power and perhaps mounting similar to the method use by the maker as shown, mounted to the cooling grilles of tv appliance so that when a mains wall switched outlet is powered, the tv or monitor and perhaps satellite or cable or ip-box also turns on. The remo-code is then ir-blasted, and reflected IR signals trigger all the remoteIR controlled devices. Using RasPI

      1. …Using RasPi seems overkill but could have been selected because that what was on hand. I think I paid 1.97us each in qty10 last bunch of attiny85micro USB purchased from Alibaba china and with proper bootload too

  2. You can turn a tv on with a candle if you really want to. Draw the pattern for the IR command [ or space your fingers accordingly ] and wave it around between the flame and the TV.

  3. What resources? The RP2040 might actually be cheaper to produce than older microcontrollers, since it has external flash and is on a newer process. It hardly matters either way, though, as low-power computers like this are basically free anyway.

  4. Orrrr just accept that modern TVs draw like half a watt when powered off and it would take 20 years to make up the cost of the parts for something like this to solve a nonexistent problem.

  5. DigiKey has atinny85 as low as 1.07/ea. Then you need parts to make it run.

    Or I can use an completed solution that just needs the IR part for $4/each.

    Yeah, I’ll take the pico too.

    1. Take a padauk microcontroller, slap an IR led across the leads, throw a few lines of code at it to fart out a 38khz pattern when powered up, done for $0.15. The most expensive part will be the power supply.

        1. Including shipping seems a bit arbitrary since these super low price point components are only really relevant for anybody planning to go into production and shipping can be as big or as small a portion of the cost as you want it to be depending on the quantity you order, but sure I’ll play. You can go to LCSC right now and buy 500 qty PMS150C-U06 shipped for $36, and 500 qty 940nm LEDs from aliexpress for $16, for a unit cost of just over $0.10. Rounding up to account for a couple passives gets you to $0.15. Obviously a hobbyist soldering components directly to one another to aim for the lowest price point possible is incompatible with how things would be done in production and you’d have to add in additional costs for PCB production, etc, but the math checks out fine for this little exercise. Unless you want me to include the cost of the entire toolchain in the unit cost now?

          1. Good job Rezer. I did the same cost analysis earlier today and arrived at about the same price per unit in quantity. I was not aware that <10 cent MCUs exist. Now I want to spend $23 to buy 250 of them shipped, just to play around. However, Padauk does not publish their programming algorithm so one would also need to invest in the programmer. No need for an emulator since I'd have 249 OTP MCUs to waste on program development :)

          2. Honestly I wouldn’t recommend actually developing for these things unless you have a real need. Hobbyists are much better off spending less time with slightly more expensive components which is the only way raspberry pis and full blown arduinos are defensible for a lot of projects, and even a bare attiny would be a hell of a lot easier while literally only costing pennies more. Even worse, any design you create using these things is unlikely to be much use to others since the toolchain is a lot less common. But yeah if the goal is simply to get it done as cheap as possible all other things be damned, it’s a difficult act to beat.

  6. From the wiring work, it also serves as a piece of modern abstract work. It depicts the artist’s aching anguish and desire to solve a complex problem while using discarded bits of large gauge solid copper wire as conductor, feet to keep the board off whatever surface it is displayed on, and handle so it can be easily carried around in an attempt to make it blend into its environment so as to loo like it is not there. If you look at it from certain angles, when the light hits is just right, you can see the artist made a very determined method to include a variety of bold colors that make it pop and thus drawing your attention to it. Thusly, just as you thought it was not there, bang! There it is. Splendid work. Genius, really.

  7. “This is frustrating when you like to leave devices switched hard off when not in use to save on standby energy draw.”

    I would be willing to bet that that always-on power-up circuit draws the same order of magnitude wall power as the standby power of the TV it is powering up. When you factor in that the standby circuit is also drawing that standby power /in addition to/ the TV when the TV is on, over time leaving the TV on standby may come out ahead in total energy usage.

    then there’s a fact that the TV has a HDMI input and CEC support, so you can turn it on with code rather than needing any hardware at all.

    1. You did not read the original post. The power-on circuit is powered on by booting his computer. So zero power use.

      Not all CEC implementations work right.

      And in general, phantom power is not as small as you think. I measured everything in my house over 10 yrs ago and it was about 200W of standby power, about the same average power as my fridge draws, ie about 33% of my power bill. Buying solar panels to produce 200w *24hr used to cost a lot more, about $2000 only in materials just to support phantom power loads. PV is cheaper now, but it’s still wasted money.

        1. wasted as in I unplugged half the things since I simply wasn’t using them on a daily or even weekly basis. unplugged = free, just slightly more annoying that I needed to turn the power strip on before I could power on the device.

          For example I had an old sony cd player that had a nice click-on, click-off power button, but it consumed 10 watts when “off”. clearly it wasn’t switching the AC side of the power supply.

          If I went a month without turning it on, that’s 7.320 kWh; money spent for no good reason. If I were buying solar panels (again, this is like 20 yrs ago when PV panels were way more expensive), I’d be paying ~$100 iirc just for phantom power / power vampires. That’s what I mean by wasting money.

      1. If you had 200W of standby power you had some seriously shoddy equipment, or you have defined standby power poorly. I would consider a house with 10W of true* standby power to be above average, 200W just doesn’t seem possible.

        *devices which appear to be off and are only waiting to be turned on and serve no other purpose in this state

        1. Drat, I can’t seem to find the document anymore, but for example our Dish Network box. It used tens of watts when “on”. and after pushing the power button and it shut the video outputs off, it still consumed the exact same amount of power. sigh. It apparently kept running so that it could keep downloading fresh decryption keys.

          I also used to put my desktop in suspend-to-RAM, and iirc it consumed like 40W (Dual Core era machine) vs 100W idling (GPU was piggy) or 300W running full tilt. so if I suspend for 16 hours a day, that’s 640 WHr, or the same as gaming at full tilt for over 2 hours. After that, I just turned the machine off. Yeah, more hassle to wait 5 minutes to fully boot, but it saved me money.

          Yes, phantom power(ish). See above about the 10W CD player too. Yes, this was still the era of iron-core transformers and incandescent bulbs, so yes, things are way better today. i.e. “but I love my 100W incandescent bulb”. me: “Are you willing to spend $1000 in PV panels so that you can power it?” (yes, bad example, since the bulb isn’t on 24/7) but multiply 10W by 24/7/365, and then across 10-20 items in the house, it gets expensive QUICK.

          1. Ah, it’s been so long since I’ve had a cable box that I forgot about the one device you can reheat your dinner on while it’s “off”. Calling that standby power is a bit dubious strictly speaking, the problem is it’s not your equipment and the dish network guys don’t give a hot shit about your power consumption, so it never goes into standby and just turns off the display. I’m unsure whether to classify that as shoddy equipment or a device which isn’t really going into standby, so por que no los dos? That said, I will concede that this is one scenario where I’d agree with the unplug while unused use case, cable boxes really are hot garbage.

            As for the PC, that is extremely surprising. I haven’t seen a PC that draws more than a watt or two in standby since I started bothering to measure around 15 years ago, and modern PCs even while idle can easily come in below that. It wasn’t occasionally on fire, was it? ;)

  8. Don’t think of it as wasting a Pi Pico just for a silly purpose. Rather think of it as keeping that particular Pico stored in a known location until you find a better task for it.

  9. I have a timer in a rack style setup. When I got a DVD surround amp combo I needed the amp to come on by the timer just like I always have. Inside the new amp I charged a cap through resistance from the 12V on board to drive a reed relay. Barely a second after power is applied it closes the power button and holds it down, it doesn’t mater. It takes many seconds to boot up but click and full sound happens. Then I don’t touch the power button only kill power by the timer. Three parts total repurposed.
    I have another home theater amp that is for the quad studio. It needs to have it’s button pressed after I turn on the whole studio power.

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