The short answer is just two. Why? Because the Sinclair ZX Spectrum power supplies are backward compatible for the two main eras of Spectrum. The power supplies that you need are both shown in the image above, for comparison.
So these power supplies are the most sought after and attract a higher price than the other types of Spectrum power supply. This is why I try to prioritise offering these in the PopeyMon Webshop and why they attract the higher price from me, because they are higher quality, have higher compatibility and have been properly checked.
Buying power supplies from dodgy sellers (e.g. on eBay) can be a bad idea for the safety of you, your family, your home and your Spectrum. And new power supplies have been sold as compatible with the Spectrum when they are not.
Original Sinclair ZX Spectrum models can be categorised into two main eras – the Sinclair ownership era and the Amstrad ownership era. The different models of ZX Spectrum are described in more detail in other PopeyMon Technical articles, such as here and here.
The Sinclair era used a barrel connector as shown in the photo of the Grey +2 power supply. This model and all previous models retained the power circuit that generated the required voltages inside the ZX Spectrum itself. The Amstrad era included the Grey +2 which (very) roughly speaking was an Amstrad version of the Sinclair era 128k “Toastrack”. It was a quick release (a “bodge job”?) to get a Spectrum out for Amstrad’s Alan Sugar to make money quickly from his newly-acquired Sinclair computer brand.
The Amstrad era after the Grey +2 used an external power “brick” similar in size and weight to the XBox 360 power “brick”. The Black +2 and Black +3 128k models used a DIN connector which generated and provided the required voltages to the main board. So the power circuit had been removed. This improved reliability of the main board, notorious for problems relating to the power circuit, especially the RAM chips and capacitors (see here for more details).
You need a Sinclair 128k ZX Spectrum +2 (grey) power supply to power the following models of Spectrum from the Sinclair era and the Grey +2 from the Amstrad era:
- rubber key Sinclair ZX Spectrum 16k and 48k
- hard key Sinclair ZX Spectrum +
- Sinclair 128k ZX Spectrum (“Toastrack”)
- Sinclair (Amstrad) grey 128k ZX Spectrum +2
And you need a Sinclair 128k ZX Spectrum +3 (black) power supply to power the following models from the Amstrad era:
- Sinclair 128k ZX Spectrum +2 (black) +2A (tape drive / Datacorder version)
- Sinclair 128k ZX Spectrum +2 (black) +2B (tape drive / Datacorder version)
- Sinclair 128k ZX Spectrum +2 (black) +3 (disk drive version)
So the long answer is also two!
As explained in the series of PopeyMon articles on Spectrum power supplies, you should NOT use the earlier power supplies on later models of ZX Spectrum.
Why? Because the maximum current ratings (the maximum current that they can safely deliver) on earlier models of Spectrum power supply is lower than required for later models of ZX Spectrum.
Using those models of power supply could kill the power supply and/or damage your Spectrum. I definitely do not recommend that you do this.
So please don’t do it!
(N.B. This is with the exception of the Sinclair ZX Spectrum 16k/48k/+ which all have the same main board inside)
You should also check your power supplies are safe to use and that they are compatible with your model of Spectrum. Remember these are using dangerous mains 240V so must be treated with caution. DO NOT OPEN A POWER SUPPLY WITH THE POWER ON UNDER ANY CIRCUMSTANCES.
If you are not sure what you are doing, please don’t do it.
Contact PopeyMon for advice.