Hi all
Hope someone can sadvise where i am going wrong, I am adding an FM detector boasrd to an AM radio via a switch at the point of the detector diode (copy of circuit attached - excuse my scribbliong hope this is ok) but i cannot get the CD4066 to switch back and forth, or actually even switch at all. I am only using two of the control pins and have put the other two to ground, have left the unused sig in / out pins as is.
Finding my way with this mod so hopefully I haven't gone way off track, it was going well until I got to the CD4066 as not used one in a circuit before.
many thanks
Mark

 

hi 3pin.
Welcome to AAC,
What are the power line voltages on the 4066.?
E

 

Your attached picture gives an error when I try to view it.

How fast are you trying to switch the CD4066?

 

The 4066 has been around for decades. This is he data sheet. Note the On resistances, could those be a problem?

Ron

 

Welcome to AAC!

excuse my scribbliong hope this is ok

That's not what would be considered a well-drawn schematic, but it's better than nothing.

it was going well until I got to the CD4066 as not used one in a circuit before

What are the supply voltages?

 

Hi
The supply voltage (Pin 14) for the cd4066 is at 9v at present, when you mention "voltages" which ohers do you require and I will have a measure.
Thank you to all for the very prompt replies and link to the datasheet, much appreciated.

 

Hello,

Is pin 7 connected to ground?

What are the input levels for the control voltage?
In the datasheet this is given :
Normal operation control-line biasing: switch on (logic 1), VC = VDD; switch off (logic 0), VC = VSS


See the datasheet for more info.

Bertus

 

Hi
The supply voltage (Pin 14) for the cd4066 is at 9v at present, when you mention "voltages" which ohers do you require and I will have a measure.
Thank you to all for the very prompt replies and link to the datasheet, much appreciated.

What is the max pk-pk voltage being switched thru the 4066?
You'll need dual supply voltages for the 4066 or bias the sinewave i/o thru the 4066.
The switch control inputs will also need to be pulled up or pulled down.

 

HI all
I will attempt to answer the questions above as best I can:-
1. Yes Pin 7 is grounded.
2. Control voltage for Ctrl A & B i set at 5V, simply connected it to a 5 V feed hope that is the way to do it.
3. Ctrl Inputs pulled down - the two unused control inputs I conencted to ground as not being used, corrsponding Input output pins I have done nothing with.
4. Max Pk to Pk voltage - can you expand please as I am still learning i.e where I would measure that, (Sign wave Peak - Peak?) but sure where I am measuring this on the circuit.
Thanks again for your help with this.

 

3. Ctrl Inputs pulled down - the two unused control inputs I conencted to ground as not being used, corrsponding Input output pins I have done nothing with.

not shown on your schematic .

4. Max Pk to Pk voltage - can you expand please as I am still learning i.e where I would measure that, (Sign wave Peak - Peak?) but sure where I am measuring this on the circuit.
Thanks again for your help with this.

The 4066 appears to be switching a bi-polar signal, ie, an audio signal. So...to switch this signal, the 4066 has to have bi-polar supplies of a voltage level at least the equivalent to the max pk voltage of the audio signal. If the signal is small enough, you might be able to bias the signal at some level to allow it to be switched.
peak to peak voltage shown below.

 

Apologies all as highlighted missed showing the two unused ctrl pins to ground on the schematic.
EEtech Do i need to measure the audio signal with my scope at the detector diode for the peak-peak reading?

 

hi 3pin,
Check Fig #18 on this CD4066 d/s
E

 

For a CD4066, the signal peaks can not be greater than the plus and minus supply voltages for the CD4066.
Also the control signal should be equal to the plus and minus supply voltages for proper switching.

 

I notice that his CD4066 is not powered on the schematic (pin 7= 0V or negative and pin 14 positive).

 

Hello,

The supply voltage (Pin 14) for the cd4066 is at 9v at present,

Control voltage for Ctrl A & B i set at 5V

With a control voltage of 5 Volts and a supply voltage of 9 Volts, no switching will take place.
With a supply voltage of 9 Volts, you will need a switching voltage of 9 Volts.

Bertus

 

Apologies all as highlighted missed showing the two unused ctrl pins to ground on the schematic.
EEtech Do i need to measure the audio signal with my scope at the detector diode for the peak-peak reading?

Measure from each 4066 switch input used to switch the signal to the signal ground reference (where ever that is).

 

Hi all
Little confused at mo with the 'peak to peak' and where I should measure it at :-i.e
1.VDD
2. Particular Control pin
3. Sig in pin
4. At the dteector diode (before or after)?
5. or somehwere else? T
To answer the post above, the power for the CD4066 is just applied to Pin 14, notice on the PDF above ground is shown as the "Low Power Pin" - should Pin 7 be ground or should I have some power there.
I will get there honest!

 

You want to measure the signal levels at the Sig In pin.

 

Ok great, I will measure in the morning as have visitors arriving shortly and report back with the readings.
Thank you to everyone who has posted so far, really appreciate it.
Have a good evening all.

 

Hi all
Measured the signal at Input 1 and Input 2, results as follows for Peak to Peak:-

Input 1 = 120mv Peak - Peak
Input 2 = 95mv Peak - peak
Also attach my scope traces although its very bright and they didn't come out that well.

Just seen the 5th post above, so I need the "Control Voltage" and "Supply Voltage" to be exactly the same voltage say 9 Volts and it should work, ok I will try that and report back as well.