would have some consideration on the noise it will create at turning it off..
thank for that....now i have some limitationIanP said:To avoid all problems you are considered of, use opto-coupled Solid-State-Relay, which can be directly driven from 8051-pin(s) ..
Here are some more details:
**broken link removed**
Rgds,
IanP
kanand078 said:hi
connect the ckt this way.
MC8051-ULN2803-O/E/N RELAY-CONTACTOR-MOTOR
Added after 15 seconds:
hi
connect the ckt this way.
MC8051-ULN2803-O/E/N RELAY-CONTACTOR-MOTOR
Added after 7 minutes:
hi
connect the ckt this way.
MC8051-ULN2803-O/E/N RELAY-CONTACTOR-MOTOR
Added after 3 minutes:
hi
connect the ckt this way.
MC8051-ULN2803-O/E/N RELAY-CONTACTOR-MOTOR
umery2k75 said:would have some consideration on the noise it will create at turning it off..
I don't know what kind of noise you mean by that?
If you are talking about collapsing of magnetic filed of Coil at shutting off, you can place a diode for suppressing high voltage generated.
umery2k75 said:would have some consideration on the noise it will create at turning it off..
I don't know what kind of noise you mean by that?
If you are talking about collapsing of magnetic filed of Coil at shutting off, you can place a diode for suppressing high voltage generated.
GrandAlf said:Opto relays offer number of advantages as described. Should the triac fail, the processor is still isolated by the opto circuit, so a good safe option. Downside is cost, cheaper to use a transistor and relay, but need careful layout to reduce electrical noise, both on the coil and switching side. Would advise the use of anti surge devices VDRs etc across contacts, as well as a coil diode.
Added after 6 minutes:
Don't need double sided PCB. All grounds to common point. Relay feed direct from psu or reg. Separate track from reg to logic, R/C decouple and lots of small decoupling caps spread around.
you mean, looping back the GND trace to PSU?, cause what i did is, i made a polygon on the PSU, then another polygon on the MCU side...Most important about grounds on pcbs, is that as far as possible, they should all go back to the psu input terminal
how can this be minimize? or elimanate, cause i saw working product, that the unit has 2 module, 1 for PSU and relay other is for the MCU, which is just connected by wires.If you have ground tracks winding all over the place, due to the resistance, earths can be at slightly different potentials. This can cause various problems in both digital and analogue circuits etc.
as you said, that MCU at start-up pins are high, i made the circuit controllable with 2 pins, 1 should be set to high and other to low to operate....if all high, relay would not be activated, if all low still it will not.You should be using one port to switch, not sure what you mean by using 2 ports?
the value of capacitor and resistor on reset pin?Sometimes you can make the reset pulse short, so that it is not long enough to operate a relay or similar. depends on processor
its helping me a BYTENot sure what the continuous pulses are, maybe some sort of instability. or a programming error. Look like you need to do a little research. Hope this helps a bit.
what i mean is that, the board for PSU, and the MCU part are just connected by wires...If you have separate boards feed power to each one direct from the psu, do not loop them
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