Hi,
My apologies if this isn't the right place, and please pardon my very limited knowledge of electronics, which has probably regressed to worse than it was when they taught us this stuff in highschool. I'm working on a project to build a Raspberry Pi into an NES. One of my goals has been to preserve the external appearance of the NES as much as possible, such that you could look at the NES and not be able to tell it wasn't original. That extends to using the original RCA ports, power brick, and power socket, if possible. For that purpose, I want to use the original NES power/RF box, using the actual power supply, and cutting the original RCA jack leads to solder in the audio/video from the Pi. I've managed to desolder one (a Mitsumi one from an NES-CPU-04).
The box seems to be in working order. When I plug it in, with the five pins in the top right, and assuming the chassis is ground (it seems to be), I see ~13.6V on the first pin, 0.26V on the second pin, and 0V on the other three. If I short the first and second pin, that seems to turn it "on", and I get 5.05V on the third pin, with the first pin dropping to ~12.8V. I understand the NES runs on 5V, so that would seem to be right.
I want to power my Pi with this thing. For that purpose, I have a small switched power supply for the Pi, which takes an input of 6V to 14V, and converts it into the 5V that the Pi needs.
I'm not sure I trust the 5V from the NES, since the Pi is apparently sensitive for voltage, so powering it directly off the NES is probably not a good idea. I'd also like to wire up the NES power switch to do a soft shutdown/bootup on the Pi, since simply cutting the power can cause problems with the filesystem. This leads me to my actual questions:
1) What's the 13.6V from? I read somewhere it's the "unregulated" voltage. This is in the range of my power supply, can I use this pin (with pins 1/2 not shorted) to power the Pi? The Pi consumes at most 10W, but in practice it'll probably be half or even a quarter of that. If I put a 5W load on this pin, is it going to be a problem?
2) If I can't use the 13.6V pin, can I semi-permanently short the first two pins, leaving the thing "on" pretty much permanently, run the 5.05V through a step-up converter to get in the range of the Pi power supply, and use that? I'm wondering if there would be any ill-effects from leaving the NES power supply on permanently. It normally wouldn't have a load on it (when the Pi is off and not in use). I wouldn't want to wire the NES power switch to interrupt the actual power, because when I release the power switch I want the Pi to do a safe shutdown and not just get the power cut.
If option 1 is fine, then that would probably be my desired option, being simpler.
My apologies if this isn't the right place, and please pardon my very limited knowledge of electronics, which has probably regressed to worse than it was when they taught us this stuff in highschool. I'm working on a project to build a Raspberry Pi into an NES. One of my goals has been to preserve the external appearance of the NES as much as possible, such that you could look at the NES and not be able to tell it wasn't original. That extends to using the original RCA ports, power brick, and power socket, if possible. For that purpose, I want to use the original NES power/RF box, using the actual power supply, and cutting the original RCA jack leads to solder in the audio/video from the Pi. I've managed to desolder one (a Mitsumi one from an NES-CPU-04).
The box seems to be in working order. When I plug it in, with the five pins in the top right, and assuming the chassis is ground (it seems to be), I see ~13.6V on the first pin, 0.26V on the second pin, and 0V on the other three. If I short the first and second pin, that seems to turn it "on", and I get 5.05V on the third pin, with the first pin dropping to ~12.8V. I understand the NES runs on 5V, so that would seem to be right.
I want to power my Pi with this thing. For that purpose, I have a small switched power supply for the Pi, which takes an input of 6V to 14V, and converts it into the 5V that the Pi needs.
I'm not sure I trust the 5V from the NES, since the Pi is apparently sensitive for voltage, so powering it directly off the NES is probably not a good idea. I'd also like to wire up the NES power switch to do a soft shutdown/bootup on the Pi, since simply cutting the power can cause problems with the filesystem. This leads me to my actual questions:
1) What's the 13.6V from? I read somewhere it's the "unregulated" voltage. This is in the range of my power supply, can I use this pin (with pins 1/2 not shorted) to power the Pi? The Pi consumes at most 10W, but in practice it'll probably be half or even a quarter of that. If I put a 5W load on this pin, is it going to be a problem?
2) If I can't use the 13.6V pin, can I semi-permanently short the first two pins, leaving the thing "on" pretty much permanently, run the 5.05V through a step-up converter to get in the range of the Pi power supply, and use that? I'm wondering if there would be any ill-effects from leaving the NES power supply on permanently. It normally wouldn't have a load on it (when the Pi is off and not in use). I wouldn't want to wire the NES power switch to interrupt the actual power, because when I release the power switch I want the Pi to do a safe shutdown and not just get the power cut.
If option 1 is fine, then that would probably be my desired option, being simpler.