## Search found 6328 matches

Wed Apr 15, 2020 6:20 pm
Forum: Beginners
Topic: Does PWM power supply divide the current drawn of a non-inductive Load along with the divided apply voltage?
Replies: 11
Views: 541

### Re: Does PWM power supply divide the current drawn of a non-inductive Load along with the divided apply voltage?

Because I thought PWM frequency is always so high comparing to the inductance of any components in the circuit like wire, air, etc. and so that we can always omit the high and low state of PWM and treat the power supply as its average voltage at anytime. What you're describing is, in essence, a swi...
Wed Apr 15, 2020 6:03 pm
Forum: General discussion
Topic: Hello and some doubts
Replies: 11
Views: 864

### Re: Hello and some doubts

Just as an aside ...
Walthary wrote:
Wed Apr 15, 2020 3:46 pm
viewtopic.php?f=63&t=224841
Wed Apr 15, 2020 10:33 am
Forum: Beginners
Topic: Does PWM power supply divide the current drawn of a non-inductive Load along with the divided apply voltage?
Replies: 11
Views: 541

### Re: Does PWM power supply divide the current drawn of a non-inductive Load along with the divided apply voltage?

Being told the load is non-inductive isn't much help, unfortunately, in part because 0.2A @ 1V applied 2A @ 5V applied Tells us it's very non-linear - not resistive (is it something like an LED?) What it would do with a supply switched by PWM isn't something I could guess at. However, you could perh...
Tue Apr 14, 2020 10:18 am
Forum: General discussion
Topic: Dual microphone noise cancellation
Replies: 15
Views: 757

### Re: Dual microphone noise cancellation

Long, long ago, when the World was young, and horses ran round Epsom Downs with crowds cheering them on - remember crowds? Lots of people all together, and no policemen telling them to go home? - microphones (unless they were rifle-mics, to pick the sound of the hooves over the twittering birds) ten...
Tue Apr 14, 2020 9:45 am
Forum: General discussion
Topic: Do the SPI Chip select pins have on board pullups?
Replies: 3
Views: 250

### Re: Do the SPI Chip select pins have on board pullups?

He means that, during power-up, both 7 & 8 are configured as inputs with pull up set. There may be some short period, from application of power to the PMIC until the SoC has done what it does and the ARM takes control, that the pins are undefined. Is there a disadvantage to putting your own pull-up ...
Mon Apr 13, 2020 10:30 am
Forum: Beginners
Topic: understanding hats and the GPIO interface / learning the jargon
Replies: 8
Views: 415

### Re: understanding hats and the GPIO interface / learning the jargon

The official PoE HAT can also be stacked with another HAT because that uses a different ID mechanism. I think. All HATs use the I2C bus that comes out on header pins 27 & 28. One address on that bus is queried at boot-up, to identify the HAT, and if more than one was connected, they'd all try to an...
Mon Apr 13, 2020 9:14 am
Forum: Other projects
Topic: Compensate for ~3 second voltage drop from power source?
Replies: 15
Views: 1014

### Re: Compensate for ~3 second voltage drop from power source?

If the Pi isn't rebooting, then the voltage drop isn't huge - just dropping below ~4.6v and triggering the detector chip. The 3 seconds you're seeing may not be an actual 3-second droop - how long does the detector chip show the fault after it's cleared, and how long does the software keep the light...
Sat Apr 11, 2020 6:00 pm
Forum: Weather station
Topic: Lightning Protection?
Replies: 3
Views: 663

### Re: Lightning Protection?

Have you got a TV aerial on that chimney? And, if so, how often has your TV been destroyed by lightning?
Fri Apr 10, 2020 6:10 pm
Forum: Troubleshooting
Topic: Simple switch with extended cable
Replies: 11
Views: 495

### Re: Simple switch with extended cable

Each capacitor has a positive and negative side. What i did is to connect the positive side of the capacitor to the GPIO pin and circle it back to connect the (2nd capacitor) negative side towards ground. Is that the correct way? I'm not sure I understand quite what you're describing, here. But may...
Sun Apr 05, 2020 5:30 pm
Forum: Beginners
Replies: 3
Views: 232

... but still I have 3.3V next to "blue" pin. Do you mean the pin labeled "GPIO2" on your diagram? If so, that may not actually a problem -it could just be normal. GPIO2 (and the next one, GPIO3) are used to talk to I2C devices; they have a resistor pulling them up to 3v3, so when they're not doing...
Sat Apr 04, 2020 9:21 am
Topic: Cannot detect interrupt properly on a pulled up line
Replies: 2
Views: 196

### Re: Cannot detect interrupt properly on a pulled up line

All GPIOs from GPIO9 upwards than the first by default have pull-downs set; this is probably why pulling out the jumper resulted in a "false" reading. It also explains the 2.7v reading when the switch is open (the internal pull-down is about 50k) It might be worth changing the pull to either none or...
Thu Apr 02, 2020 9:03 am
Forum: Automation, sensing and robotics
Topic: Values in the ADC are fluctuating and incorrect.
Replies: 9
Views: 640

### Re: Values in the ADC are fluctuating and incorrect.

A capacitor would be to remove high frequency noise. In your first picture, I can see 3v3, GND, SCL & SDA reaching the ADC board, then A0 & A1 wandering off-screen.They go, I assume to your sensor? The matrix board has four blue wires going off-screen, and two connectors, one with a black cable also...
Wed Apr 01, 2020 5:31 pm
Forum: General discussion
Topic: Please just ignore (some) 1st posts
Replies: 56
Views: 2815

### Re: Please just ignore (some) 1st posts

Was going to count all those with zero posts, and those with just one, just to get a handle on the statistics. But gave up after boredom set in. I would imagine zero posts, more than a year's membership, would number many, many thousands I would imagine many people automatically join any site they c...
Wed Apr 01, 2020 8:59 am
Forum: General discussion
Topic: Please just ignore (some) 1st posts
Replies: 56
Views: 2815

### Re: Please just ignore (some) 1st posts

jbudd wrote:
Tue Mar 31, 2020 9:47 pm
More than 160 000 forum members!? Is that like a slow burn denial of service atack?
Just this minute reached 290400
Thu Mar 26, 2020 10:17 am
Forum: General discussion
Topic: what happened to the raspberry pi 4 1GB?
Replies: 23
Views: 1505

### Re: what happened to the raspberry pi 4 1GB?

If new cars are better than old ones, does the same apply to buildings?

And, if so, should we knock down Stone Henge and replace it with an apartment block?
Thu Mar 26, 2020 9:48 am
Forum: Troubleshooting
Topic: Simple switch with extended cable
Replies: 11
Views: 495

### Re: Simple switch with extended cable

0μ1F = 0,1μF = 0.1μF = 0u1F Half the world uses a fullstop as a decimal separator, while the other half uses a comma. The rest of the world can't find either of those on their keyboard, so they put the multiplier (p, n, μ, m, k, M, G, T, ...) in its place. And many of us can't find the μ so we use u...
Thu Mar 26, 2020 9:33 am
Forum: Beginners
Topic: Controlling 24V AC Solenoid Valve by solid state relay
Replies: 3
Views: 252

### Re: Controlling 24V AC Solenoid Valve by solid state relay

gannonziviello wrote:
Tue Mar 24, 2020 9:24 pm
... The power supply is a standard American wall outlet.
Should we interpret that as a "wall-wart", plugged into a socket and producing 24V AC on the end of a pair of wires?
If so, as long as it can supply enough current for the two valves, safety should already have been taken care of.
Thu Mar 19, 2020 10:08 am
Forum: General discussion
Topic: Problem with GPIO and relay
Replies: 22
Views: 1109

### Re: Problem with GPIO and relay

http://www.farnell.com/datasheets/2626620.pdf?_ga=2.180659879.1406569187.1584567076-883246931.1584567076 On page 5, the table gives 40mA for the 5v version. That's far too much for a GPIO to supply - 16mA is the most you should take from a GPIO. As pcmanbob says, you need a driver circuit between th...
Tue Mar 17, 2020 10:06 am
Forum: Wanted
Topic: Control/interface board for 7" display
Replies: 6
Views: 1484

### Re: Control/interface board for 7" display

A piece of cardboard could be used to jam the ribbon in place - not too thick, but thick enough, you'll have to experiment.
Sat Mar 14, 2020 6:42 pm
Forum: General discussion
Topic: So, what's the big new thing for this year's Pi Day (8th anniversary) ?
Replies: 130
Views: 9388

### Re: So, what's the big new thing for this year's Pi Day (8th anniversary) ?

MRV wrote:
Sat Mar 14, 2020 8:56 am
3.14 - 9:53 am - Italy
Woke up.
Went to the kitchen.
No new pies.
Back to sleep.
The devil's in the detail.
Eighth Birthday means you should have gone to bed with eight lit candles, four on each side, ready for blowing out in the morning.
Not sure whether they're with or without the forks
Fri Mar 13, 2020 11:41 am
Forum: Troubleshooting
Topic: Mfg part number for inductor L1 rpi 4B
Replies: 1
Views: 190

### Re: Mfg part number for inductor L1 rpi 4B

Yes, I believe it's L1, but unless one of the RP engineers says different, all we know is what's on the diagram.

Though I would be surprised if the only damage is the broken L. Most likely, you've also broken the chip aswell
Tue Mar 10, 2020 6:54 pm
Forum: Troubleshooting
Topic: Offical Rasberry Pi 7in'' Touchscreen Flickering with relays
Replies: 31
Views: 1196

### Re: Offical Rasberry Pi 7in'' Touchscreen Flickering with relays

The Relay has to get power from the pi to be controlled by the Pi I've tried powering it separate as well. It is connected via GPIO pins and the 5v pin ( it does not work with the 3v3) it is also grounded on one of the pi's ground pins. The Amazon 4-relay board has a "JD-VCC - VCC" link. If you rem...
Tue Mar 10, 2020 12:04 pm
Forum: Other projects
Topic: RP as Atomic Clock broadcast
Replies: 5
Views: 579

### Re: RP as Atomic Clock broadcast

One problem you might not have thought about: So you successfully create a 60kHz signal for your own clocks, and they're locking to it correctly. But just down the road, someone else's clocks now have two signals to lock to, and they can't know which is correct. If all else fails, that someone also ...
Mon Mar 09, 2020 10:46 am
Forum: General discussion
Topic: Power 3x RPi Zero W from mains 230VAC
Replies: 10
Views: 661

### Re: Power 3x RPi Zero W from mains 230VAC

I believe the "illegal" claim was in reference to installing a hidden camera inside a fake light, which is indeed illegal, but only if you do not inform people the area is being surveiled. Although that kind of defeats the purpose of it being hidden, doesn't it. Do I have to inform potential burgla...
Sat Mar 07, 2020 6:50 pm
Forum: Troubleshooting
Topic: Yellow bolt and undervoltage detection
Replies: 22
Views: 1235

### Re: Yellow bolt and undervoltage detection

the batteries are two pieces of 4200mah so it should be 8400mah total but i don't know why the Raspberry and the monitor stay on just for 1 hour. It seems this device support max 8A and i think that change the batteries with others with higher amperage will not help. How could it be that 8400mah la...