4069 blowing frequently

[CMOS]

high input impedance amplifier 4069

Hi
I have constructed "X10 Home Automation System" (AN236) from Microchip. The system is working perfectly fine but now I am facing trouble with 4069 CMOS inverter that is used to demodulate X10 data from power line. When I switch on the mains supply and if there is arcing in the switch contacts, 4069 goes dead. This has happend for more than 10 times. MOV has been used in the circuit but I think it is of no help against these voltage spikes. The power supply used is transformerless. The schematic of 4069 section is shown below.
How do I deal with this problem?

 

[Borber]

linear cmos 4069 4049

You may try to use protection with resistor and two diodes.

 

[CMOS]

4069 bandpass

Will the above circuit affect the sensitivity of the demodulator? Can I use 1N4148 instead of BAT41?

 

[bobcat1]

4069 chip schematic

Hi

No it is not effect the signal only clemp the input signal to the power supply rail



All the best


Bobi

 

[IanP]

4069 input voltage

You can use 1N4148 diodes and I would decrease value of this resistor from 4k7 to 100Ω ..

 

[CMOS]

4069 tuned filter

Hi All,
I am still facing the same problem. Even a small arcing in switch contact blows up the 4069. I think the power supply section also needs some modification. The spike may be entering through it.

The power supply schematic has been posted here

Any suggestions please?

 

[CMOS]

4049 vs 4069

Anyone please. I have to submit this project next week.

 

[Borber]

cmos 4069 problems

First try to detect destroying pulse with oscilloscope. Is it on input gate or on supply voltage.
Next try to find out is blown chip destroyed totally or only one the of inverters. Is blown input inverter or any other. In this way you can maybe find out is the destroying pulse comming on input or throught supply. I think the layout can cause the problem too.
Connect destroyed chip on 5V and test it's functionallity.

 

[CMOS]

how to use a 4069

Hi Brober,
That seems to be the most professional way of debugging. But I am really falling short of time. Is there anything that I can connect across the switch to stop arcing?
Or the last thing left with me is carry a full strip of 4069s during demonstatration and replace whichever blows up.

Regarding the damage, it happens only to the signal input gate of 4069.

 

[Borber]

4049 vs 4069 invertors

To avoid excessive arcing on switch you may connect accross it a series connection of 10-100nF and 100Ω. Try it.

 

[FANT]

inverter 4046 zenner diode

Instead of 4069 use the 4049 that has the input overvoltage protection and put a zener with a voltage higher of about 2-3 V than the power supply across the supply pins.
I know, the pinout is different, but I have never had problems with the 4049.

Mandi

 

[Rope]

inverter circuit 4069

Use a HF transformer separation at the 4069 input. See the NE50XX line modem from Signetics aplications at the linear data book.

 

[artem]

4069 cmos

Your zener doides on carrier data could be useless because of fast raise time when switching - s could be case zeners are not fast enough to cut glitch .

Spike protection with 2 diodes could be useless as well because they are connected to 5 V and i do nto know impedance of your 5V siupply . If it is quite high and not filtered for high freq - spike will be transferred to 5 V supply as well .

Try to make fiollowing :
a. To decrease raise time on tuned amplifier input
put low bandpass filter (just simple RC) assuming it will pass X10 working frequency .
b. Cut spikes after that bandpass by sequentially connected fast switching diodes (there are 4 of them shown below - increase or decrease to get required cut voltage threshold)

like

Carrier Data -> LP filter (RC)-> circuit below

<------> to tuned amp
| |
A V
A V
A V
A V
| |
------- Ground

c. Additionally put good quality HF filtering capsitor on your 5 V supply (Would be better if you can analyse it for short pulse filtering behaviour )

d. you haev additional inverter 4046 . If it is unused - connect its input to ground .

Finally there are 2 possible ways (at least visible from your schema) to burn 4046 :
- power 5V
- input from carrierdata

you have to secure both to keep 4046 alive .

 

[yousefkamil]

we have the same project but we face some problems can u help us to find a solutions for these problems and thank you