Running a Spectrum from a battery...?
Here's a bizarre idea that crossed my mind the other day: is it possible to run a Spectrum from a 12V battery?
You see, I've got this strange idea that one day I will own a camper van or multi-utility van of some sort, and if it's possible for Max Power / Revs / Redline teenagers to wire a Playstation into their bodykit-enhanced Citroen Saxos, surely it must be possible to do the same with a Spectrum?
I'd have thought the +2A/B would be ideal, seeing as it uses a 12V power supply rather than the 9V of previous models - or is the DIN connection going to be more of a problem than the simple plug that those older models used? One thing is fur sure, it would be very wasteful to run the battery into an inverter and then plug the regular +2A/B/+3 power supply into that.
You see, I've got this strange idea that one day I will own a camper van or multi-utility van of some sort, and if it's possible for Max Power / Revs / Redline teenagers to wire a Playstation into their bodykit-enhanced Citroen Saxos, surely it must be possible to do the same with a Spectrum?
I'd have thought the +2A/B would be ideal, seeing as it uses a 12V power supply rather than the 9V of previous models - or is the DIN connection going to be more of a problem than the simple plug that those older models used? One thing is fur sure, it would be very wasteful to run the battery into an inverter and then plug the regular +2A/B/+3 power supply into that.
Comments
Unless earlier issue boards are known to had the "mandatory" power supply upgrade modification, it's not wise to power these with any input voltage over 11.8V.
If you can get your hands on a good quality switching regulator that is rated at 1.5A, then I think the 128k toastrack or the grey +2 can then also run from a 12V DC supply.
The later Amstrad +2A, +2B and +3 officially need three supply voltages: +5V, +12V and -12V. The -12V is only needed for the serial/MIDI/Aux/Keypad ports. The main logic runs from the +5V rail. So a 5V switching regulator circuit would be needed to supply the logic circuits. The specifications of the chips that require a +12V supply would need to be checked, to see if they could run from the +12V external supply. Because a boat 12V supply can vary between 11V to 14V and at times may have large voltage spikes, or voltage dips as high current motors etc are switched on or off.
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
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Looking forward to summer in Somerset later in the year :)
However, what starts as an "it is possible, but..." from someone who knows a thing or two about electronics becomes a "no" when applied to those of us who don't.
By "boat power supply" do you mean a huge leisure battery that's recharged by a generator, or some similar setup? That's not quite what I had in mind, I was thinking of connecting a separate battery straight to the Spectrum without having it power anything else - which should eliminate those voltage spikes, although a fully charged battery should be more like 13.5V than 12V, and when discharged I've seen it as low as 8V.