Thats a CT with isolated primary and secondary .I pass the current carrying wire through the air gap of the torroid and a scaled voltage appears across the secondary...
So theres no issue there i guess
(anyways...a bit off topic....please check the other thread about DAC current )
[QUOTE {snip}
The switching of Linear loads like tungsten lamps works fine but other loads like Fans,Fluorescent lamps reset the MCU. {snip}
[/QUOTE]
I have had similar problems and the only solution was to in-case the circuit in an iron metal shield, nothing else worked. I used the sheet metal from an ordinary food can and I only had to wrap about 3/4 of the the small plastic box the circuit was mounted in.
Make sure the can is iron by checking with a magnet
Thanks Rolf for the crucial info
I will sure try it.
I actually forgot to tell a very important thing about the ckt,
I am using an unisolated 5V PSU for thisthing.
Will this matter?
I know that electronics in washing m/cs use this kind of setup
Thanks and regards
No.
Unisolated meant ;no step down transformer for the PS.
I use a PI Buck conv.chip operating at 60KHz to get me 5V from 230V AC.
So ckt ground and the mains neutral are same.
I have seen electronics in washing m/c use an unisolated PS for the microcontroller and the relay ,the only addition they use there is using a ZCD switching for the relay.But the noise on the GND line never malfunctions the microcontroller.
What could be wrong?
I imagine D5-7 is your problem. It does not compensate for transients on the 5v line created like that of the un bypassed relay circuit will generate. Use an LDO for your 3 volts. Add a bypass on the Relay + side first and see if that works. Otherwise get an LDO.
The problem is, your MCU needs a nice clean stable power supply. It is my feeling that you can not get this without a good regulator. You may be able to get around this with playing with filters on your supply, but you could save yourself much trouble with a proper regulator. How much could one cost? Before anything else, try and filter you relay + terminal, that might help. If it were me I would just use a regulator and be done with it.
I am sure the 5V supply is fine. The problem is your 3v supply is not. You will need to play games to get your 3v supply clean, best thing is a regulator. If your 5v sags or surges when the relay energizes, this sag or surge will be on your MCU supply.
Maybe you can play with many cap values on the relay + pin plus +5v but this is just a band aid, best thing is like I said.
It is common practice to isolate digital supplies and analog supplies for this very reason. Your diode scheme offers little to no isolation of power supply noise.
I really don't know why you are firm on using a non isolated power of 5V direct from230V /110V AC.
In fact even if you use any cellphone adopter, you get a good isolated power and these adopters are now a days very cheap. Use a resistor and 3.3V zener with a 1uF cap to get your 3V supply instead of three diodes. Always ensure that 0.1 is just across pins 5and 14 not far away to either of the pins.
Anyways theres also a weird problem with this ckt.
I switch a relay and theres a incandescent lamp in the contacts.When I switch this on/off it does it well.But when I try an Inductive load,the MCU jumps to a routine simulating a key press,which is an active high switch,when used.
Is this also relating to the current issue?...or something else...???
Anyways Thanks so much for taking interest in my woes...