I'm looking around for an inexpensive frequency counter to use for audio experiments, and hoping for some recommendations.
There's lots of little circuits around, but they seem to be mostly for RF.
Probably can't afford the $$ (or space) for an old HP bench type (I wish).
I notice that some modern meters have a frequency function, but I have never actually used one so I don't know how appropriate they might be for measuring small signal audio.
Your experience?
Thanks,
Keith
There's lots of little circuits around, but they seem to be mostly for RF.
Probably can't afford the $$ (or space) for an old HP bench type (I wish).
I notice that some modern meters have a frequency function, but I have never actually used one so I don't know how appropriate they might be for measuring small signal audio.
Your experience?
Thanks,
Keith
Why do you need a frequency counter for audio measurements in the first place? What frequencies do you want to measure and what kind of accuracy do you need?
For measuring T/S parameters, for viewing waveform distortion with a scope, for playing around with filters, that sort of thing 🙂
It's not so much about accuracy as it is to check for consistency and keep a watch on equipment faults and user error...
It's not so much about accuracy as it is to check for consistency and keep a watch on equipment faults and user error...
I was wondering and thinking similar to what Marcel has asked. If you just want repeatability and (what ?) 1% accuracy then I think the frequency range on a DVM would be fine. My meter has that facility and its pretty accurate.
I also have an ancient Simpson 711 counter that goes up to 80Mhz with good accuracy. I calibrated it (back in the day, can't do this now of course) using the locked chroma sub carrier oscillator in a CTV which in the UK was precisely 4.43361875Mhz when tuned to a BBC transmission.
The range on a DVM should do all you want.
I also have an ancient Simpson 711 counter that goes up to 80Mhz with good accuracy. I calibrated it (back in the day, can't do this now of course) using the locked chroma sub carrier oscillator in a CTV which in the UK was precisely 4.43361875Mhz when tuned to a BBC transmission.
The range on a DVM should do all you want.
Hi Kieth,
I'm using an HP 5385A that I got for about $110. My 34401A has a fast frequency counter good up to 300 KHz (so free with the meter) and my expensive counter is an HP 5335A with a "C" channel. My new-ish Keysight and Agilent hand held meters have counters good up to 100 KHz. My scope has a 5 digit counter built in (Agilent 54642D) - so free with the scope. The Tek 2465B CT has a counter built into it too.
So with all that, I would point you towards the HP 5385A. It's a newer LCD display type and has HP's reverse counting technique. For the low hundreds, I can't see you doing any better. Especially at low frequencies! Keep an eye on Ebay and some of the discount sellers in used test equipment.
-Chris
I'm using an HP 5385A that I got for about $110. My 34401A has a fast frequency counter good up to 300 KHz (so free with the meter) and my expensive counter is an HP 5335A with a "C" channel. My new-ish Keysight and Agilent hand held meters have counters good up to 100 KHz. My scope has a 5 digit counter built in (Agilent 54642D) - so free with the scope. The Tek 2465B CT has a counter built into it too.
So with all that, I would point you towards the HP 5385A. It's a newer LCD display type and has HP's reverse counting technique. For the low hundreds, I can't see you doing any better. Especially at low frequencies! Keep an eye on Ebay and some of the discount sellers in used test equipment.
-Chris
If your oscilloscope has cursors, you could use those to measure frequencies to within a percent or two. Just put two cursors on adjacent rising zero crossings.
Thanks guys!
Yea, an HP5385A would be nice...
RE DVM: The specs that I've seen (not many) on DVM's tell me the freq range they measure but don't tell me the level required to get a good reading. So it's good to hear that you find them adequate- I'll need to do more homework on that. If you have a recommendation on an inexpensive DVM that will give reasonable accurate freq counter for the audio range at a little under one volt that would be great...
Yea, an HP5385A would be nice...
RE DVM: The specs that I've seen (not many) on DVM's tell me the freq range they measure but don't tell me the level required to get a good reading. So it's good to hear that you find them adequate- I'll need to do more homework on that. If you have a recommendation on an inexpensive DVM that will give reasonable accurate freq counter for the audio range at a little under one volt that would be great...
Hi Kieth,
Just keep your eyes open for one. Then you have something that does RF too. I use a X10 'scope probe on mine so I don't upset the circuit, it has a 1 Meg input for the low band, 50R for high frequencies. It's the perfect bench freq. counter and it has a fast update rate which makes adjustments easier to do.
I see most are ranging from $140 to $250 on Ebay right now. Probably still well worth it if you can afford it. Remember, you will own it for 30 years or more.
-Chris
Just keep your eyes open for one. Then you have something that does RF too. I use a X10 'scope probe on mine so I don't upset the circuit, it has a 1 Meg input for the low band, 50R for high frequencies. It's the perfect bench freq. counter and it has a fast update rate which makes adjustments easier to do.
I see most are ranging from $140 to $250 on Ebay right now. Probably still well worth it if you can afford it. Remember, you will own it for 30 years or more.
-Chris
I'm using the old HP5315A and it's fine for my very simple needs. If you want to try something small and cheap, there's this and many similar on eBay:
1Hz-50MHz Crystal Oscillator Frequency Counter Tester Digital DIY Meter Kit Tool | eBay
I have no experience with these tho.....
Phil
1Hz-50MHz Crystal Oscillator Frequency Counter Tester Digital DIY Meter Kit Tool | eBay
I have no experience with these tho.....
Phil
Hi Phil,
Ahhh, those are using a u-controller instead of a frequency reference and divider chain. I wouldn't count on the accuracy at all. Also, the low frequency count will be a lot slower than the HP counters. Or any counter for that matter.
-Chris
Ahhh, those are using a u-controller instead of a frequency reference and divider chain. I wouldn't count on the accuracy at all. Also, the low frequency count will be a lot slower than the HP counters. Or any counter for that matter.
-Chris
Hi Phil,
The price was too good to be true, and I have bought clocks using those chips as little projects. They aren't accurate, and they aren't terrible either. But, as a frequency counter I would trust them.
-Chris
The price was too good to be true, and I have bought clocks using those chips as little projects. They aren't accurate, and they aren't terrible either. But, as a frequency counter I would trust them.
-Chris
Beware the $85 "8 digit" frequency counters like this one. They don't actually display frequencies with 8 digits except in very rare cases, near the upper limits of a frequency band. Otherwise you get five or sometimes four digits on the display.
As soon as I discovered this limitation, I abandoned the cheapie counter and bought a reconditioned HP5335A for $340 from diyAudio member John Bau (his site is linearz dot com). 200 MHz, 12 digits, now THAT'S a frequency counter.
My application? Measuring the values of small (15 nH) unknown inductances by resonating them with a known capacitance, and measuring the resonant frequency on the HP frequency counter.
diyAudio thread: Measuring the ESL inductance of electrolytic caps (at 10 MHz!)
As soon as I discovered this limitation, I abandoned the cheapie counter and bought a reconditioned HP5335A for $340 from diyAudio member John Bau (his site is linearz dot com). 200 MHz, 12 digits, now THAT'S a frequency counter.
My application? Measuring the values of small (15 nH) unknown inductances by resonating them with a known capacitance, and measuring the resonant frequency on the HP frequency counter.
diyAudio thread: Measuring the ESL inductance of electrolytic caps (at 10 MHz!)
The old HPs are nice because most are reciprocal counters and are fast even with low frequencies. They don't usually sell for too much. OTOH, for occasional use, download a free copy of Visual Analyser which has a counter and much more if you have a sound card.
I'd strongly suggest using or adding a soundcard and software approach - I know that REW software can automatically lock on to and determine frequency of signals in spectrum mode, including harmonic levels when there is a dominant signal, and also noise levels. A picture (plot) can be worth a thousand discrete measurements - so to speak, and it also easily shows up spurious signals above the noise floor that you may not have observed otherwise (as the S/N range is so much larger than a scope, or would ever be triggered by a counter). The sweep capability to give an automated frequency response is just so easy for filter assessment.
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It seems to me that the OP would be better served by a generator
with a reliable frequency display. HP3325 A/B, for example.
Cheers,
Gerhard
(SR620, 12 digits in 1 second) 🙂
with a reliable frequency display. HP3325 A/B, for example.
Cheers,
Gerhard
(SR620, 12 digits in 1 second) 🙂
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The one and only problem with sound cards is protecting the input. You have to be constantly aware of the voltage of the signal you're probing. And the fact that most sound cards are about 10K input impedance.
-Chris
-Chris
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