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It was the C10 voltage switching. U6 didnīt switch back and forth.
It was rectangular waveform, 50% duty cycle at oscillation frequency of U4 pin 4.
Now with C11=30 nF and Resistor the behaviour canīt be reproduced.
Good, lets see the big picture now, and if the locked circuit is independent of RV7.
1407 #1: OK, does the circuit lock into frequency when circuit is turned on ?
1407 #2: Can you affect the frequency with RV7 when in lock and D6 on ?
@tecstatic
good structure!
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
#1: yes, it does when RV7 is turned to GND; no it doesnīt when RV7 is turned to VCC
#2: yes turning RV7 affects frequency but not linear, seems to jump to and fro in frequency
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
#1: yes, it does when RV7 is turned to GND; no it doesnīt when RV7 is turned to VCC
#2: yes turning RV7 affects frequency but not linear, seems to jump to and fro in frequency
bussi04
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
OBS1410 #1 Note: comparing phase at pin3 and pin 14 of U4 while turning RV7 to match phase fails. Phase always flips away immediately before phases could match.
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
OBS1411 #2 starting at 4212 hz and RV7 at GND frequency raises to 4900 hz, then flips back to 4303 hz while tuning RV7 in direction VCC.
Please use full question number, so we can refer to it many posts later when trying to make reason in what we observe.
#2: yes turning RV7 affects frequency but not linear, seems to jump to and fro in frequency
A little more info is nice like e.g.
"Q1407 #2: yes turning RV7 with D6 on and no spikes on U8 pin 3, affects frequency but not linear, seems to jump to and from in frequency, xxxHz@RV7=0V, yyyHz@RV7=5V"
Note: comparing phase at pin3 and pin 14 of U4 while turning RV7 to match phase fails. Phase always flips away immediately before phases could match.
Good, please number your observations also e.g.
"OBS1410 #1
Note: comparing phase at pin3 and pin 14 of U4 while turning RV7 to match phase fails. Phase always flips away immediately before phases could match."
We now must find the reason to the dependence upon the RV7 setting.
It can be the lock is not done, or it can be some problem related to the switchover.
Please be very observant on the conditions around U6, GND OK, VCC OK, pin 5 stable "1", pin 13 stable "0", RV7 not affecting U6 pin 1 .
Now you had to wait, because you answered by editing a previous post, I did not notice that.
Please don't "reuse" posts by editing, it breaks the sequence of reasoning.
And let's post in a ping/pong fashion.
Please redo the measurements observing:
Please be very observant on the conditions around U6, GND OK, VCC OK, pin 5 stable "1", pin 13 stable "0", RV7 not affecting U6 pin 1.
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
I did the following measurement:
"Q1407 #2: yes turning RV7 with D6 on and U8 pin 3 at GND without spikes,
Small positive spikes at 4563hz@RV=1.5V, instability at U8 pin 3 at 4987hz@1.90V (frequency shift at U4 pin3), stable 1.4V at U8 pin 3 at 4297hz@1.28V (D6 off), 1.2V stable without spikes at U8 pin 3 at 4236hz@1.18V, 1.8V stable at U8 pin 3 at 4826hz@2.2V, thenU8 pin 3 instant jump to GND at 6330hz@4.55V.
now I redo the measurement observing pin 5 and 13 of U6.
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
I did the following measurement:
"Q1407 #2: yes turning RV7 with D6 on and U8 pin 3 at GND without spikes,
Small positive spikes at 4563hz@RV=1.5V, instability at U8 pin 3 at 4987hz@1.90V (frequency shift at U4 pin3), stable 1.4V at U8 pin 3 at 4297hz@1.28V (D6 off), 1.2V stable without spikes at U8 pin 3 at 4236hz@1.18V, 1.8V stable at U8 pin 3 at 4826hz@2.2V, thenU8 pin 3 instant jump to GND at 6330hz@4.55V.
now I redo the measurement observing pin 5 and 13 of U6.
Now we are in business, good quality answer seen from a remote location, super
I would not even consider making a switchover circuit this way. May I suggest we bypass the switchover circuit and let the 4046 do the job on its own.
MOD 1415#1:
Connect the wire going to U6 pin 3 to U4 pin 4, being the only connection to U4 pin 4.
Now we are in business, good quality answer seen from a remote location, super
I would not even consider making a switchover circuit this way. May I suggest we bypass the switchover circuit and let the 4046 do the job on its own.
MOD 1415#1:
Connect the wire going to U6 pin 3 to U4 pin 4, being the only connection to U4 pin 4.
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
Added capacitor 100 nF between pin 14 (VCC) and pin 7 (GND) of U6
OBS1414#1: very short (means while edging) spikes (0.8V) at GND pin 7 of U6 at the rising and falling edges of signal at pin3 of U4.
OBS1414#2: very short (means while edging) spikes (0.8V) at VCC pin 14 of U6 at the rising and falling edges of signal at pin3 of U4.
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
Added capacitor 100 nF between pin 14 (VCC) and pin 7 (GND) of U6
OBS1414#1: very short (means while edging) spikes (0.8V) at GND pin 7 of U6 at the rising and falling edges of signal at pin3 of U4.
OBS1414#2: very short (means while edging) spikes (0.8V) at VCC pin 14 of U6 at the rising and falling edges of signal at pin3 of U4.
now I do MOD1415#1 and call back when done.
From OBS1414#1 and #2 you get a glimpse of the necessity of a proper GND plane, also observe the way you connect your probe plays a big role in what you see on the scope, when looking for transient signals like the spikes here.
With MOD 1415#1 done,
Q 1417#1: What is the signals and frequency at U4 when turning on power ?
Now we are in business, good quality answer seen from a remote location, super
I would not even consider making a switchover circuit this way. May I suggest we bypass the switchover circuit and let the 4046 do the job on its own.
MOD 1415#1:
Connect the wire going to U6 pin 3 to U4 pin 4, being the only connection to U4 pin 4.
U8 pin 5 reconnected to U8 pin 6
Pin 2 of RV7 connected to VCC
U2 in circuit again
Set center frequency to 5600 hz
R15 = 4.7 KOhm
R15 cut off from U8 pin 4 and connected to U7 pin 11
C10 = 500 nF
C10 connected to pin3 of U6B
R14 = 100 KOhm
C11 = 30 nF
D5 in series with Resistor 1 KOhm
Inserted Resistor 1 KOhm between C11 and pin5/6 of U8
Added capacitor 100 nF between pin 14 (VCC) and pin 7 (GND) of U6
MOD 1415#1: Connect the wire going to U6 pin 3 to U4 pin 4, being the only connection to U4 pin 4
Done, but donīt understand: U4 pin 4 is frequency output and mixed to U4 pin 13 pulses integrated by C10.
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