HP 3325A Bonus Material: Fractional-N Frequency Synthesis for Dummies

[@maksymkloka7819]

OMG! I can't find an amazing video I saw on how fractional N divide circuits work. Nothing comes even close.

[@electronash]

This video explains in only 8 minutes what it took my college tutor to explain in 8 lessons. lol Really enjoying these educational vids. Keep up the good work.

[@NinerFourWhiskey]

I have to admire the kind of engineering that went into this. I've built mostly consumer products in my career, with lots of marketing input. I have to wonder what the meetings were like back in the day that this was designed.

[@jimmy_jamesjams_a_lot4171]

Something awful must have happened at HP. They don’t make RPN calculators anymore. Their version of my printer’s toner cartridge doesn’t work. And they just don’t make gear like that anymore, nor do they publish any operator’s manual that doubles as a service manual and does so in an illustrious 500 or so pages with quite some painstaking detail. No wonder why I feel so overwhelmed all the time! Thanks for a great PLL lesson!!

[@geo48geo48]

A PLL, who don‘t wobbeling with a high factors like 300 and 400 is great! You need a very stabile VCO.

[@dustysparks]

You could say, the HP was originally... incapacitated.

[@dustysparks]

...I'll see myself out.

[@stephendavies923]

You managed to make me realise just how much I had forgotten since my time in electronics in the 80's. Thanks for helping me relearn again.

[@AlanMimms]

Beautifully simple explanation of an elegant concept. Thanks Marc.

[@chrissavage5966]

You'd enjoy the synthesis of colour subcarrier frequency (4.43361875MHz) from the centrally generated 'Natlock' reference signal that the BBC used to use....... I recall having to work it out for an exam many years ago. Sadly, age being what it is, I now have no clue!! :) I can recall it had a large a complicated selection of dividers and PLLs. The idea was that you ended up with every contributing regional broadcast centre running with the same, locked, colour subcarrier. It meant you could put sources from all over on your mixer and just needed to do a simple phase shift to get them all timed up. Way back in the analogue days.

[@kaitlyn__L]

That’s really interesting! I suppose the economies of scale made that cheaper than genlock circuitry for the colour carrier in every studio?

[@davedrezTV]

Fantastic! - I love the storytelling, with the twist at the end... simply a bad capacitor... who would have guessed? Thanks for all the great videos and information. You work so hard for our entertainment and education.

[@MoraFermi]

. . . Anybody watching Mr. Carlson's Lab with any regularity? :-)

[@dentakuweb]

That was explained very well. I've always found PLLs to be such an elegant circuit. In the music/synthesizer world, VCOs are considered finicky things but it's nice that they can be useful even in very accurate test equipment. You've inspired my to see if I can build something like a basic a PLL with an XOR, a lowpass filter and a basic VCO.

[@AdrianChallinor]

This is fascinating. It takes me back to computing and electronics at university 77-80! I had forgotten all my PLL stuff, but that was a great explanation. Thank you.

[@davidkilpatrick1640]

Great video and clear explanation, thanks Marc!

[@jagardina]

Thanks, you made that surprisingly easy to understand.

[@leozendo3500]

Best PLL explanation.

[@va3dxv]

Very interesting! I picked up one of these a couple years ago, super cheap. I didn't think they were that highly regarded. Thanks for the great info!

[@MatthijsvanDuin]

3:30 Hmm, if my math is right the DC component of the output of a mixer whose inputs have the same frequency is proportional to the cosine of their phase difference, which seems problematic for locking on since it just gives you the absolute error rather than the signed error, hence you wouldn't know which way to correct. Am I missing something?

[@MatthijsvanDuin]

oh duh, you lock them 90 degrees out of phase

[@MVVblog]

Simple and clear!

[@missamo80]

Being posted on April 1st with that video thumbnail I had to do a double-take and make sure this wasn't a gag :)

[@gcewing]

It's a meta-april-fool -- makes you think it's april foolery when it's not!

[@0MoTheG]

Had this on my bench for years. The only time it broke it was the power contact in the back that had oxidized and then burned out.

[@admirerofclassicalelectron2858]

This video was highly useful for me. And entertaining, too. Thanks!

[@skfalpink123]

I wonder how much of this wonderful HP equipment has ended up being scrapped for looking too much like “old school”?

[@ElectricEvan]

my lab director threw out 3 or 4 of them before I caught up with him. the remaining 4 were split up among the engineers so we each have at least one at home now.

[@Spookieham]

A criminal amount unfortunately.

[@dgaborus]

HP 3335A has exactly the same technique, and has a detailed description in the service manuals.

[@ReneSchickbauer]

Very good explanation. Thank you!

[@chriholt]

Thanks for the clear explanation!

[@glenwoofit]

Great explanation, Thanks.

[@video99couk]

It's when you mentioned the Pulse Remover Circuit that I realised it was an April Fool's Joke. It was, wasn't it? I mean, nothing could be this complicated!

[@CuriousMarc]

No April fool here, this is actually how it works!

[@video99couk]

@@CuriousMarc I know, I was just being silly. It is an extraordinarily complicated piece of kit and I just thought the Pulse Remover Circuit seemed like a strange solution, but I'm sure it all makes sense if you drill down into the deepest detail.

[@km5405]

wait you have a extra channel with extra gems of knowledge?

[@grlg2]

Very Interesting! This is why I love this channel. Cheers.

[@ivanpopovic504]

HP back in the day made great instruments with some of the worst possible power supplies. Arguably the worst of the worst power supplies HP ever made was the one in 3325A. Also have to say for 12 yrs. in using and repairing HP, 95% of fails were in power supplies. :(

[@DAVIDGREGORYKERR]

the MC145106 does exactly that.

[@smilingdog2219]

What are the practical applications for Frequency Synthesizer?

[@CuriousMarc]

Very important circuit in modern RF. It allows you to generate a digitally controlled, arbitrary tunable reference frequency from a single quartz crystal. You have one in every radio, WiFi, cell phone, etc…

[@DanielPalmans]

Marc I love all your video!!

[@lloydtshare]

Cool thanks, but what would use it for?

[@dustysparks]

Producing very precise frequency signals, mainly for testing and calibrating other equipment, rarely as a thing you need on its own (at least at the price point this piece would retail at).

[@Digital-Dan]

I used it as a quick and dirty hearing test at the end. It almost reached the pitch of my tinnitus. :-)

[@_a.z]

Great subject!

[@nophead]

It would be nice to recreate this with a GPSDO and an FPGA.

[@MLGJuggernautgaming]

Keep the elevator music explanations coming

[@twobob]

I love you but you drew a high pass filter. Assuming LTR interpretation is a given. That must have been the Vc graph and I missed it ;)

[@Nottsboy24]

Interesting upload 👓🎓🔬🔭

[@pulesjet]

Dang, Real Brain Food. Just using Heterodyning to generate the higher frequencies.

[@ronvanwegen]

I'm afraid I missed the last part of the video as I accidentally got off at Ladies Lingerie.

[@Joemama555]

Its really hard to watch anything technical on April Fool's day that you don't already know about....

[@tehlaser]

Nifty