Magazine Archive

Home -> Magazines -> Issues -> Articles in this issue -> View

Short Circuit

A 1kHz Test Tone Oscillator

From time to time, you'll need a 1kHz tone to line up recording equipment. Sometimes, the necessary tone is available from the gear itself, whilst more elaborate mixing consoles feature test tone generators, although these are rarely very accurate. If you do not have access to a 1kHz tone though, the circuit here may fit the bill. Its high accuracy (1kHz +/-3½%) is down to using 2½% tolerance polystyrene capacitors, which are both cheap (most high tolerance capacitors cost an arm, and a leg) and readily sourced. For lower spot frequencies, you should scale the resistors (160k gives a 100Hz tone), as capacitor values above 10nF won't readily come in a 2½% tolerance. The frequency determining resistors must be 1% tolerance types, as marked on the diagram.

The only expensive part, the RA53 thermistor is, sadly, not readily substituted: it offers high purity of tone, which helps when you're trying to listen for/track down distortion by ear. The LED is to help remind you not to flatten the battery, which should last 12-18 months with prompt yet regular use. The LED current, incidentally is set at a pretty minute 8mA, so as not to accelerate the power consumption unduly. If you intend to drive the tone generator into long cables - greater than ten feet say - replace the TL071 or LF351N op-amp with an NE5534N, and reduce the output resistor from 330R to 47R.

(Click image for higher resolution version)

More with this topic

Browse by Topic:

Electronics / Build

Previous Article in this issue

AMS RMX-16 Digital Reverb

Next article in this issue

Constructing a 'floating' studio floor

Home & Studio Recording - Copyright: Music Maker Publications (UK), Future Publishing.


Home & Studio Recording - Mar 1984

Feature by Ben Duncan

Previous article in this issue:

> AMS RMX-16 Digital Reverb

Next article in this issue:

> Constructing a 'floating' st...

Help Support The Things You Love

mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.

If you value this resource, you can support this project - it really helps!

Donations for January 2022
Issues donated this month: 2

New issues that have been donated or scanned for us this month.

Funds donated this month: £137.00

All donations and support are gratefully appreciated - thank you.

Magazines Needed - Can You Help?

Do you have any of these magazine issues?

> See all issues we need

If so, and you can donate, lend or scan them to help complete our archive, please get in touch via the Contribute page - thanks!

If you're enjoying the site, please consider supporting me to help build this archive...

...with a one time Donation, or a recurring Donation of just £2 a month. It really helps - thank you!

Small Print

Terms of usePrivacy