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Guys thanks for the input, I built a capacitive dropper to regulate the signal to 5V, limited the current to minimum with limiter power resistors at both AC arms. The current is sufficient to drive EL817 optoisolators (i think it's a china version of the PL817, but with only one channel). I...
Thanks guys, I will be making the PCB for the system, if the problem persists I will post the circuit here.
Is there any precaution on placement of components in designing the PCB?
Thanks, I found the problem with the program freezing using the watchdog timer... Turns out the oscillator was faulty.
Now back to the malfuction... Even with the oscillator replaced, the PIC still goes haywire when someone turns on or off anything randomly..
What does it mean 20MHz gives problem? I've always used 20MHz for PIC16F877A but never encountered this...
So do I get another 4MHz oscillator to replace the 20MHz crystasl?
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Hi,
Thanks for pointing the antenna issue, I never knew that...
So if making them on PCB solves...
I have Brown out reset configured to OFF in the config word. How do I achieve proper power line filtering? I don't think it is the problem with the power, since the same problem occurs when i power the system with a UPS, not connected to the mains. Purely run on the UPS backup battery.
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Hi all, I have come across a really weird phenomena... I am working with a project with PIC16F877A,
which sounds a buzzer, lights up two LEDs (different output ports), lights up a 24V pilot lamp (optocoupled) and energizes a relay (transistor) when it detects a signal.
The power supply is a...
Thanks, I would like to try all methods one by one... but the component suppliers here are simply too not competitive... Imagine they don't even have optocouplers and triacs in store...
I would like to tryout a capacitive dropper, which the components are more of a hope to be available here...
Thanks for the suggestions, I think there is PC817 around my area, since it might be the only thing available, I must have a go on it. However in the datasheet it is stated that the absolute maximum rating for forward current is 50mA, how do I know the minimum current needed to switch on the...
Hi, I'm working on a project to control valves, one at 240Vac and another at 24Vdc. The system is controlled with a PIC microcontroller. I have been searching for info on interfacing microcontrollers to the industry world, but found literally nothing. Why isn't there anything about this? How do...
Thanks for the sharing, appreciate it :D
About the resistors at both the DC arms, i will have 230*230/(47000*2)W of power to be dissipated, which is 0.56W. So is using the normal 1/4W resistors fine? Secondly, how do I decide the suitable value for the capacitor?
Ops sorry, had to think 1000 times faster to meet the dateline :-o
Does that mean, it's ok even if I don't add a capacitor after the rectifier? Let the rectified signal pulsates, the first 5V pulse triggers the alarm, and it sounds the alarm until the system is being reset, I wouldn't need to...
Brian,
Yes I do realize that the circuit related to the mains requires isolation and that is why I prefer optoisolators.
I am building a control unit to be mounted in a junction panel for gas detection system. However the signal from the industrial gas detector sensor gives a signal of 230Vac...
Geez, no wonder my resistors are charred as coal...
I have another problem, the resistors available to me now are the usual 1/4W type, connecting one in each 230Vac arm they can sustain 1/2W, the resistance I will need is
V²/R = 1/2
R = 105.8kOhm (literally)
However the current flowing through...
Thanks, I will give it a try.
I recently came across a transformerless design where 230vac is stepped down to low voltages with capacitors and resistors.
There 230vac is connected to (1M Ohm resistor and 400V 334J capacitor in parallel), then series with a 1K Ohm resistor, then into a bridge...
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