Switching with CD4066

Thread Starter

hamopp

Joined May 13, 2009
68
Hi
Thanks for the replys
Are these inputs connected to two separate radios that do not have a common ground?
No, this is for one radio only.

Also, need to know if the SEL voltage levels change between when there is no traffic (not transmitting) and traffic (transmitting).
The select voltage levels do not change between Rx and Tx

I don't know what the levels of the signals are that you are putting in on the various SEL lines
Sorry i forgot, the FM, SSB\CW select lines are +12v dc from a ULN2981A chip (But at the moment from a 1p 4w switch for testing)

Heres a re-post of the current state 4066 schematic

Regards
Howard
 

bertus

Joined Apr 5, 2008
21,588
Hello,

The S-meter connections will not work.
An S-meter signal is DC, it will not pass the 10 uF capacitor.

Bertus
 

SgtWookie

Joined Jul 17, 2007
22,221
The S-meter still won't work then.

The TL07x opamp can't get within 3v of the negative rail. You'll have to change the opamp you're using.
 

Thread Starter

hamopp

Joined May 13, 2009
68
You need to take care the input signals for the S-meter are positive only.
Bertus
yes input signals for the S-meter are positive only.

The thing is that i need to sort a fix out for the prob of the diodes and
4066 blowing

I have also tried a version with relays (my design) (NEW RELAY.png) but this also seems
to have the same problem, when i power on in FM mode, rly1 and rly2 switch ok
and the FM audio and FM rssi are ok, but as soon as i switch to USB the diodes D3,D4
and D5 blow, but if i remove D2 from rly3 and rly4 D3,D4 and D5 don't blow,is this to do
with back emf ??
So i think it has something to do with D3,4 and 5
but why do they not blow when i remove D2 ?
Regards
Howard
 

bertus

Joined Apr 5, 2008
21,588
Hello,

From what circuit are the control signals coming from?
Note the 1N4148 are rated 100 mA only, when using the relays version that may be short.

Greetings,
Bertus
 

SgtWookie

Joined Jul 17, 2007
22,221
Either that, or you have installed D2 backwards. That would cause a short to ground.

For the relay reverse-EMF, try using 1N400x series diodes; x=1 to 7. They are very cheap and available everywhere.
 

Thread Starter

hamopp

Joined May 13, 2009
68
Hi

Bertus:
From what circuit are the control signals coming from?
They come from a ULN2981A line driver, which in turn are driven from a
PIC16F628P, but i am using a 1p 4w switch at the moment!.
Note the 1N4148 are rated 100 mA only, when using the relays version that may be short.
2 relays only draw 65mA, thats why i used IN4148's, but thinking
again that might be a bit to close to the max of the IN4148's. Do you think
i should use IN4002's for D3, D4 and D5 (relay version) and D1, D2 and D3
(4066 version) ??

SgtWookie:
Either that, or you have installed D2 backwards. That would cause a short to ground.
I made sure that the diodes are installed the right way round.
For the relay reverse-EMF, try using 1N400x series diodes
If you look at the relay circuit you will see that i have used IN4002's (D1, D2) across the relay coils.

Regards
Howard
 

Thread Starter

hamopp

Joined May 13, 2009
68
Hi

Right i have just got some IN4001A's from a friend, and replaced the 3x IN4148's
with them, and the relay circuit is now working :cool:

Both relays that are on the FM Select, draw 66mA, and the 2 on the SSB\CW
Select, draw 62mA, with a supply of 13.95v, will be 12v when i get some
7812's.

The supply to the FM Select relay's is 13.95v (no diode), and to the SSB\CW
Select relay's is 13.18v (with diodes).

When any of the SSB\CW diode's are selected, the other 2 have about 0.5v
on the select input lines (cathode's), is this gonna be a prob with the ULN2981A line
driver ic that powers the select lines ??

Regards
Howard
 

SgtWookie

Joined Jul 17, 2007
22,221
That should be OK. The 1N400x series has a bit of leakage, and so does the ULN2981A. No big deal, as long as the diodes are in there.
 
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