4069 4046 Oscillator not working.

[guidoilieff]

Hi. I made this oscillator with modulation but cant get it to modulate. I can vary the pitch of the tone tough.







Here are the ic's voltages:

4069:

1- 6.1
2- 2
3- 2
4- 1
5- 0.5
6- 9
7- 0
8- 9
9- 1.5
10- 1.5
11- 4.4
12- 9
13- 5
14- 9



4046

1- 9
2- 0
3- 0.5
4- 4.5
5- 0
6- 1
7- 1
8- 0
9- 9
10- 8
11- 7
12- 7
13- 0
14- 4.5
15- 2.5
16- 9



2n3904
all legs 9v


Tested for shorts and there were none so I have no idea what's wrong with that transistor.

My only theory is a mistake with the switches but I asked the author and told me they are on-on-on and that's what I bought.


Any idea? Thanks

[diffeq]

I don't see any errors in the layout (yet).

Does the LED blink/change brightness? De-solder S2-B switch wire and if it doesn't, then 4069 does not oscillate and you should check the pot, cap and diodes in 4069 path. 

EDIT: C3 shall be non-polarised, not electrolytic capacitor.

[anotherjim]

I think those switches should be SPDT centre-off ,  or, "on-off-on". The mid position MUST be off. With on-on-on switches, you can never have normal LFO sweep operation and S2 would short VCC to Ground in the mid position.

I can't see a triangle/square LFO option in the schematic - it's always connected to the triangle output (which becomes a positive or negative ramp with switch S1 up or down. Switch S2 should put a high or low frequency offset on the VCO when not in centre.

If you completely remove S1 and S2, then you should have normal (up-down sweep) siren operation.

[guidoilieff]

I don't see any errors in the layout (yet).

Does the LED blink/change brightness? De-solder S2-B switch wire and if it doesn't, then 4069 does not oscillate and you should check the pot, cap and diodes in 4069 path. 

EDIT: C3 shall be non-polarised, not electrolytic capacitor.

The diode doesn't blink or change brightness. I used a 0.22uf cap (224) for C3 instead of the 1uf (105). Could that be the problem? I can't find any 1uf non polarized cap.

[diffeq]

C3 is frequency-setting in this oscillator, along with P1 potentiometer. If you set it smaller it still should oscillate, just faster.

What version of 4069 do you have? 4069BE or 4069UBE?

[guidoilieff]

C3 is frequency-setting in this oscillator, along with P1 potentiometer. If you set it smaller it still should oscillate, just faster.

What version of 4069 do you have? 4069BE or 4069UBE?

4069UBE

[thermionix]

How can a SPDT be on-on-on?  That would just be 3 lugs always connected, not a switch at all.

[highwater]

How can a SPDT be on-on-on?  That would just be 3 lugs always connected, not a switch at all.

I can think of one way:
1) Lug 1 connected to lug 2
2) All three lugs connected
3) Lug 2 connected to lug 3

(edit-to-add: to me, at-least, on-on-on switches are one of the top-5 most confusing things in electronics... a multi-megawatt RF transmitter would be easier for me to understand)

[anotherjim]

on-on-on are the mini toggle pickup selectors on some guitars. There, they are wired to work just like the usual Switchcraft lead/both/rhythm pickup selectors used by Gibson et al. They may have 4 tags instead of 3 or look like DPDT with 6 tags. Wired so that in the middle, both circuits are made. Flip up or down, only one or the other is made.

[guidoilieff]

Whats the difference between those 4069 ics? I cant find it on the internet

[thermionix]

2) All three lugs connected

Ah yeah, I didn't think of that.  I'm used to the DP style like in Jim's post, which doesn't really tanslate to SP.

[ElectricDruid]

Whats the difference between those 4069 ics? I cant find it on the internet

Buffered (BE) and unbuffered (UBE).

HTH,
Tom

[diffeq]

Whats the difference between those 4069 ics? I cant find it on the internet

As I understand it, the 4069UBE is unbuffered version of this inverter -- it works like inverting opamp stage and the 4069BE is buffered version and it works just in two logic states (HIGH and LOW). You have the right one.

[duck_arse]

my understanding is that the 4069 does not* have a buffered version.

The HCC/HCF4069UB consists of six COS/MOS inverter circuits. This device is intended for all general-purpose inverter applications where the medium-power TTL-drive and logic-level-conversion capabilities of circuits such as HCC/HCF4049B Hex Inverter/Buffers are not required.

from the ST/SGS-Thomson datasheet.

* just in case.

[ElectricDruid]

It seems Duck's right. I had a hunt for datasheets and the only reference I can find for "UBE" is a note saying that the "E" suffix indicates the plastic DIP package "UBE", instead of ceramic which is "UBF".

Sorry, typical naming patterns are not followed in this case. Moral: as ever, always read the data sheet.

T.