Firstly, hi everyone, I am new here so go easy on me,
I have just recently started to play with electronics and am completely absorbed by the vast subject, how I never got the bite before eludes me. So onto my problem.
I am trying to reduce the heat generated by a heat sink in an old Sinclair ZX Spectrum. The computer's power is fed from an unregulated power supply that has the following specification
Input : 240v AC 50Hz
Output: 9v DC @ 1.4A
When measuring the output of various identical Sinclair Spectrum power supplies I found that the voltage varies between 12 and 16 volts. I know that the 7805 regulator knocks the voltage down to 5V and loses the rest as heat and that the voltage from the power supply lowers as more energy is drawn from the said power supply. This is what is causing the heat sink to get quite hot and ruin the keyboard cables and the caps.
So, how am I able to modify this scenario? I think I am looking at three different angles, see below
1. Modify the Power supply 'add a series diode to drop the energy slightly'
2. Modify the Spectrum 'replacing the 7805 with a better less wasteful component or components' I don't want to modify circuits that change the speed of the spectrum.
3. Create a device that sits between the power supply and the spectrum that would lower the power output of the power supply.
As I say, I am brand new to electronics and haven't even finished getting all my tools sorted
Thanks in advance for any help on this guys, the subject might be very simple but I have a love of these machines and I feel that It's a good place for me to start
Kindest regards to all