4046 Phase locked loop

[acl]

Hi there,

We have had several requests for the 4046 devices used in Peter Smiths motor control circuitry. I have found that due to the unconventional mode we are operating these devices in there are varying degrees of performance between different supply manufacturers. Those of you using these chips in your equipment I would like to take a poll of devices that perform well by posting the manufacturers reference on this site.

Regards Chris Lewis

Screenshot 2024-09-29 093638.jpg (41.78 KiB) Viewed 268 times

[acl]

CD4046BE very poor frame locking

MC14046BCP excellent frame locking

I will look at whether the disc input signal is different between devices.

[Steve Anderson]

Hi Chris, I have a few thougts on this which I'll address in the (my) morning, I have an event to attend in a few minutes time...

Steve A.

[acl]

Thanks Steve,

It may just be R3 needs trimming

[Steve Anderson]

It may just be R3 needs trimming

That may be a 'fix', but it's not the answer. Two things spring to mind. the speed of the transistion of the opto sensor, and likewise the 'sync input'. Even at 12V old HEF/CD devices are sloth-like, stop using them. Or use an ECC88 (faster). That is almost, but not quite a joke.

A TIL100 with a 1M load is going to have a response time of...who knows into an ill-defined following stage? Also a TIL100 is an IR device... a comparator with some hysterisis between the TL100 may help, may.

Steve A.

[acl]

Thanks Steve

[Steve Anderson]

In other words, it seems that everything downstream of R3 is OK. The headache is in the 4046 and/or it's inputs. I would suggest most are related to the inputs, however variable inputs to a 4046 will result in variable outputs. It is a linear operation conducted with logic dopants, not ideal. Though a breakthrough in the 70s, but not now. However, there is no reason why it shouldn't perform within its design parameters. Just get the inputs correct and it should work! i.e. RTFM.

Steve A.