Hi all,

I bought a Sinclair ZX81 on a garage sale some days ago for around 12 USD as a non-tested item as the guy said he had no wires to even try and run it. I have a couple of RF cable kicking about from my Atari 2600 and ZX Spectrum, so I have this basis covered.

According to the manual LINK it takes 9V 700mA unregulated (I’m not sure what it means) 3.7mm jack power supply. I have a 9V DC 1A jack power supply I bought for the Atari (it’s not an original one - a unbranded one) and I tried to use it, but to no success. Manual tuning my TV same as with Spectrum and Atari, and no signal.

I was wondering if maybe the power supply is not up to spec? I was thinking that maybe 1mA is too much to power it up? But I went online to look for an unbranded ZX81 power supply and they are running 2A so I’m not sure what’s going on here.

Is it busted? Or should I get one of those unbranded power supplies that say they are made for ZX81 to test it?

Thanks :)

  • Galapagon
    4·
    10 months ago

    Amps are how much you can push Volts are how hard you can push

    If you push too much, the device won’t use everything If you push too hard, something is likely to break!

    That’s how I try to remember. It’s a bit more complicated because you’re not wasting 1.3a if it’s only using 0.7. and I’d have to do the math but for example in some cases you could use (for example without checking math) 10v power supply and only use .6 amps

    In your case go with what agentsac is saying, but I don’t think you need to worry about max amps.

    • neidu2@feddit.nl
      2·
      10 months ago

      I like thinking in hydraulic equivalence: Voltage is the water pressure, and Amperes is the amount of water. Multiply the two and you get the size and ferocity of the river.