freestompboxes.org

Does anyone know the origins of the project?

I have seen the entire article somewhere that explains the circuit, but can't seem to find it again. It looks interesting with the inductor. There is a simple vero layout, too.

The schematic and vero are attached.

Thanks!

The problem with using an inductor is that it will be prone to picking up magnetic hum. Also, inductors can be fragile, and expensive. A simpler approach is to use a frequency dependent bypass for the emitter resistor in a simple transistor amplifier:
Obviously, you can change the value of the 4k7 emitter resistor and the 47n capacitor to alter the frequency response.

jrod wrote:Does anyone know the origins of the project?

I'm fairly sure it came from "Practical Electronics".

Thanks for the schematic and info, mictester. I was also thinking Practical Electronics.

Is the inductor used to get the treble frequencies? I think I like your approach better!

jrod wrote:Thanks for the schematic and info, mictester. I was also thinking Practical Electronics.

Is the inductor used to get the treble frequencies? I think I like your approach better!

It's used as a crude high pass filter.

The other approach is to make the input coupling capacitor smaller than it should be, so that treble frequencies get through more than lower ones. You then recover the lost level with a simple single stage amplifier. That's the approach taken with the "Rangemaster" and several other products, but can only give a slope of 3 dB per octave. Other methos can give 10 dB per octave!

mictester wrote:

jrod wrote:Thanks for the schematic and info, mictester. I was also thinking Practical Electronics.

Is the inductor used to get the treble frequencies? I think I like your approach better!

It's used as a crude high pass filter.

The other approach is to make the input coupling capacitor smaller than it should be, so that treble frequencies get through more than lower ones. You then recover the lost level with a simple single stage amplifier. That's the approach taken with the "Rangemaster" and several other products, but can only give a slope of 3 dB per octave. Other methos can give 10 dB per octave!

Interesting! Thanks for the help and info!!!

mictester wrote:The problem with using an inductor is that it will be prone to picking up magnetic hum. Also, inductors can be fragile, and expensive. A simpler approach is to use a frequency dependent bypass for the emitter resistor in a simple transistor amplifier:

Treble_Boost.jpeg

Obviously, you can change the value of the 4k7 emitter resistor and the 47n capacitor to alter the frequency response.

Had a go at this one, very nice booster indeed The single dial provides a useful range adjustment/kind of a tone control. I'm assuming this has a high input impedance as it really makes the guitar pickups ring out nice and clear.



I went old school on the boxing up of this one, I put it in one of those folded steel project enclosures somewhat like the Rangemaster ones. No bypass on this, the slide switch simply turns the power on, so its either on or not - its very nice so for cleanish tones I can see me having this on all of the time. I put the Cornish buffer in front of it just because I had the board laying around and was tidying up my odds and ends, you don't need it, the booster on its own is just dandy.

It's old school mojo to use an inductor with make up gain
usually not as much but/and more
[ not as practical or cheap but definitely different feel ]

Its not the one from the magazine article, but from the schemo Mictester posted using the BC109 transistor.

kaycee wrote:Its not the one from the magazine article, but from the schemo Mictester posted using the BC109 transistor.

Excellent! I'm glad you like it!

I have one here, which my Wife calls the "Jangly Box" because it gives that nice 60s jangle with my Rickenbacker!

Yes, I found it very nice with a Tele on the bridge through a compressor (JangleBox clone). I like it better than my various Rangemasters - Shock Horror You have another version up somewhere on here that doesn't have the 10k on the input and has a 2u2 out from the collector and no cap across the pot, thats nice too.

kaycee wrote:

Hey man whats that enclosure? and did you paint it yourself or buy it painted? its very cool!

Actually it looks like a chassis from maplins?
http://www.maplin.co.uk/aluminium-boxes-1728

Another variation of a frequency-dependent bypass:



I implemented this on my build of Gus Smalley's NPN Boost. Re is end lugs of gain control pot. Wiper goes to the range control circuitry.

Thank you mictester for providing the schematic that I used. Sorry if there are any mistakes. First time to convert a schematic to a layout and also to use software. Use at your own risk.

Cut under C4, sorry

Here is the complete article, from Practical Electronics, April 1972

---

Interesting, a different treble booster circuit.
Here the data of the transformer:
https://www.petervis.com/electronics/lt ... ormer.html