hi
i need some help on this circuit note i found that pin 12 on cd4060 should be on gnd and did put a 3.9 meg res with the xtal. It is to read 15hz to 400hz but it keeps reading 300hz to 400hz thats it on it

thanks



http://www3.telus.net/public/a5a2631...REQCOUNTER.pdf

 

looks to me like pin12 is the reset and should be set accordingly, not necessarily ground?

 

Hi,
but can you say why it would not give the right FRQ on it
i did look on hear but could not find post on this problem??

 

Hi Kid-kv,

Your timebase, the CD4060 isn't working because it's reset function
is active. This is what the datasheet says about the reset:

"A RESET input is provided which resets the counter to the all 0's-state
and disables the oscillator. A high level on the RESET line accomplishes
the reset function."

There is a high level on the reset line, so change it to a low level.
And that's not all, there are two resistors missing, the oscillator is
probably working on another frequency.

on1aag.

Attached Images

CD4060B oscillator.GIF (7.5 KB, 21 views)

 

hi on1aag
what would the resistors be in size or just use what the datasheet shows??

this is part of a tig welder circuit


thanks

kid-kv

 

Hi Kid-kv,

Start with one single resistor accross the crystal, use a 1 M and
see what it does. Later you can insert a 1 k resistor for Rs.

on1aag.

 

hi, on1aag
ok will do so
thanks for all the help

Kid-Kv

 

ok, that did not work if an ic was bad witch one do you think would it be?????
I put a dmm with a square wave out put of 50hz and it gave me 18 to 30hz so whats up guys ??????????

kid-kv

 

Hi Kid-kv,

The output frequency of the CD4060 should be 4 Hz. At the output(s)
of the first '112 you should measure 2 Hz and 1 Hz at the output(s)
of the second '112. If that's ok you should take a closer look at the
input signal, it should be at TTL level.

on1aag.

 

The output frequency of the CD4060 is 8hz and the 112 is 4hz how do i take and fix this????

Kid-kv

 

It is essential that you carefully check that what you built is exactly as the schematic shows. Check every connection and the actual value of every resistor and capacitor against the schematic. Once you have done that, here are some more ideas:

- if you are measuring 8 Hz at pin 3 of U3A, then your oscillator may be running at a harmonic (which is very unusual so I have my doubts about this) or you are simply measuring the output at pin 2 rather than pin 3. The values for C2 and C3 are good choices for this kind of crystal, but I do agree that a resistor across the crystal is necessary. I think your 3.9M should be fine. How is the circuit constructed? Is it built on a solderless breadboard, on a vectorboard pcb or on a custom pcb or something else? I ask because you have to minimize stray capacitance on the pins 10, 11 and 9. Solderless breadboard has way too much stray capacitance for this.
- that you are measuring 4Hz at U4B pin 7 indicates that U4A and U4B are working properly as their job is to divide by 4. I was a bit concerned that you might have substituted a CMOS IC at U4 which would require that all of those no-connect inputs be wired to either +5V or GND and not left floating. TTL will function correctly with inputs floating as we see here, although it is bad design practice to do so.
- I note that U5B has several inputs floating. This is unacceptable and may cause U5A to malfunction which would mess up the reset pulse to your counter chip. You should ground U5 pin 13 and pull U5 pin 11 to +5V, as required by the data sheet instructions.

If the only fault was that your time base is running at twice the expected frequency (that is, U3 pin 3 is outputing 8Hz instead of 4Hz), then your counter would always display values exactly half of what was expected. Is this the case? If the values jump all over the place and are not consistent, then I would also suspect something is wrong with the operation of U5A.

One other thing to mention is that this counter will only count signals that are large enough in voltage swing to toggle the input to U1A. I doubt that this IC is designed for small analog signals, so be sure that your inputs are swinging up and down from 0 to about 5volts or so. You should be able to measure your input's amplitude at around 1.5 to 2 volts ACRMS on a DMM. If you read a lot lower, then perhaps your simply not giving the counter enough input level. Its also worth mentioning that the input is expected to be a 0 to 5volt swing of voltage centered around 2.5 Volts. If you are AC coupling the input, you may not get correct function.

__________________
RadioRon

 

hi, RadioRon
I did look over the board and its ok..
the board is a custom pcb all leads are short that i did kept in mind when i did it..
will be back with more when done

Kid-kv

 

the input's amplitude is 2.70 ac all pins are right did put a new 4060 same thing.
and no AC coupling

 

hears a pic of the board done with eagle

Attached Images

board.png (25.3 KB, 17 views)

 

what if i took out the 4060 and used a 555 timer to get the 4hz would that work
the 22pf caps will not show up on my dmm as 0.022 nf

the display now shows 85hz to 100hz and did the pic of the board help??

Kid-kv