Optimum supply voltage?
Optimum supply voltage?
I'm trying some transmission tests across the bench on 2.4 GHz, using just the Lime Mini output into a small rubber duck antenna and receiving on Minitiouner/Minitioune.
A static testcard decodes fine. The constellation looks good. MT shows no red error bar or error lights.
I've increased the supply voltage to the RasPi4, screen from 5.1V to 5.2V. The power goes to pins 4 and 9 on the GPIO connector. The Lime is supplied from the USB2 socket on the RasPi4.
PD4 Info still says "Low supply voltage now".
The 7" screen shows a little yellow lightning bolt in the top RH corner. Is that a low voltage indication?
What is a safe maximum voltage? I have a 5.6V zener crowbar.
Graham
A static testcard decodes fine. The constellation looks good. MT shows no red error bar or error lights.
I've increased the supply voltage to the RasPi4, screen from 5.1V to 5.2V. The power goes to pins 4 and 9 on the GPIO connector. The Lime is supplied from the USB2 socket on the RasPi4.
PD4 Info still says "Low supply voltage now".
The 7" screen shows a little yellow lightning bolt in the top RH corner. Is that a low voltage indication?
What is a safe maximum voltage? I have a 5.6V zener crowbar.
Graham
Re: Optimum supply voltage?
For the PI4, 5.3V - but you shouldn't be seeing the lightning bolt at 5.2V. Are you sure it really is 5.2V? In any case it appears to be working OK. Next test some moving images?
Re: Optimum supply voltage?
Power supply problems can occur when the internal resistance of the powersupply(inlcuding the wiring to the PI) is too high. This is hard to see with a multimeter. Use a good supply and thick wires. Also an electrolitic capacitor of 1000uF or more soldered directly over tho power input connector of the PI helps.
The capacitor delivers the short current pulses the PI draws.
Rob K
PE1CHY
The capacitor delivers the short current pulses the PI draws.
Rob K
PE1CHY
Re: Optimum supply voltage?
Hi Graham
For the Raspberry Pi 4, I always feed the supply volyage to the GPIO pins. Then I use thick (RS 16/02) supply leads from a low impedance power supply.
I set the supply voltage to be 5.2v at the pins under load. Finding a well regulated power supply for 5.2v at 2 or so amps then becomes the major challenge.
Brief transients below 4.8v (ish) will trip the low voltage monitor, but should not cause major issues. A continuous lightning bolt shows that the voltage is continuously low and needs attention.
Dave
For the Raspberry Pi 4, I always feed the supply volyage to the GPIO pins. Then I use thick (RS 16/02) supply leads from a low impedance power supply.
I set the supply voltage to be 5.2v at the pins under load. Finding a well regulated power supply for 5.2v at 2 or so amps then becomes the major challenge.
Brief transients below 4.8v (ish) will trip the low voltage monitor, but should not cause major issues. A continuous lightning bolt shows that the voltage is continuously low and needs attention.
Dave
Re: Optimum supply voltage?
I have thick wire to a bit of connector block where the voltage is measured, then spindly DuPont wires to the GPIO, so there may be a slight voltage drop to the GPIO. I'll move the DVM wires to the GPIO & investigate further.
A capacitor on the RasPi is a good idea.
Thanks to Mike, Rob and Dave for your tips.
73 Graham
A capacitor on the RasPi is a good idea.
Thanks to Mike, Rob and Dave for your tips.
73 Graham
Re: Optimum supply voltage?
Dupont wires from Ebay? If so, I am surprised they have not melted. That's your problem.
Re: Optimum supply voltage?
I swapped out the few cm of flimsy wires & put an even shorter length of fatter wires in, with an extra low-ESR capacitor near the GPIO for good measure.
Neither the RasPi nor the screen complains about high voltage now.
What would make it tidier would be a break-out connector for the GPIO connector. At the moment, I have a collection of 1F and 2Fs pushed onto the pins. I may have a board somewhere. I know I bought some other bits of board from Dave at Finningley a while back.
Thank you for your help.
73 Graham
Neither the RasPi nor the screen complains about high voltage now.
What would make it tidier would be a break-out connector for the GPIO connector. At the moment, I have a collection of 1F and 2Fs pushed onto the pins. I may have a board somewhere. I know I bought some other bits of board from Dave at Finningley a while back.
Thank you for your help.
73 Graham
Re: Optimum supply voltage?
This sort of thing ?
Re: Optimum supply voltage?
Very natty with the fan Mike!
I'm sure I have a board somewhere...
73 Graham
I'm sure I have a board somewhere...
73 Graham