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First oscillator!

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joshd963

New Member
Hi, well firstly im new here, so.. hi all! :)

i've been interested in music for a while now and im a fan of experimenting with sounds, and now i want to take it a bit further to the analogue world and perhaps one day have something i can use live! i understand that it will take a long time to learn to this stage, and im willing to start out very basic, i find it really fun messing with stuff and taking stuff apart anyway! So in short, i would like to start out first by making a basic battery powered oscillator with a potentiometer controlling the frequency.. and at some stage i would really like to add some sort of cutoff filter.. a VCF is it called?

I appreciate any help at all and im a big newbie and a picture of a circuit to me is .. daunting! id also like to learn to read circuits, and one day be able to contribute back to the community!

i look forward to your replies :D cheers
 

BrownOut

Banned
Most noobs cut their teeth by building an astable multivibrator ( I did ) It's a very versitle curctuit which can be modified to do just about anything from generating a sirene to an electric organ. There are alot of examples on the web and on this forum. Other good choices are a astable build in a timer such as a 555, or a wien-brige oscillator build around an operational amp. Most any low or medium opamp will do. Look up some of these curcuits and see which piques your interest.
 

joshd963

New Member
Thanks for a quick reply!

some of those words hurt my brain... im way out of my depth here, my depth is... a puddle or shallower.

a quick google of wien-brige oscillator gave me this circuit diagram on a wikipedia page..

8285-Wien_bridge_classic_osc.png


i assume R is a resistor, C is a capacitor, dots are wire connections, upside down triangles are power?(unsure).. but ive no idea what the rest is? :S

also had a quick google towards whatever an opamp is.. im from the UK and Maplins is my best bet for components i think, would this do the trick?

**broken link removed**

any help is appreciated! any newbie books you could recommend i would be happy to dedicate my time to :)
 

marcbarker

New Member
I thoroughly recommend you build a Theremin.

Theremins are so awesomely cool they are bad!

I mean you don't even have to touch the instrument to play it, you just put your hand near the vertical antenna to control the pitch, and your other hand near the circle antenna to vary the character.

You can hear a Theremin playing on 1966 Beach Boys song Good Vibrations, it sounds like 50's SF movie soundtrack and is spooky.

If you want to build something like this in a hurry, you can get two transistor radios, tune them so that they give interference to each other (a loud tone in the speaker), and have the antenna attached to one of them, even a piece of wire sticking up will do. You have to find where to attach the wire, you bascially dob the wire by trial and error onto different places until you find a part of the circuit that is sensitive to "stray capacitance"
 
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joshd963

New Member
theremins look pretty awesome, id like to build from scratch and i found a tutorial that even has a parts list.. i just find the circuit diagram confusing!

im sure i could manage my way round it but before i order all the bits, is this a good / fairly easyish build to get started and get familiar with all the bits with?

cheers for all your help peopleeee
 

blueroomelectronics

Well-Known Member
Oscillators can be strange things, when you try to build one they may refuse to oscillate, on the other hand if you're building a DC power supply they seem to like to oscillate :)
 

BrownOut

Banned
Thanks for a quick reply!

some of those words hurt my brain... im way out of my depth here, my depth is... a puddle or shallower.

a quick google of wien-brige oscillator gave me this circuit diagram on a wikipedia page..

8287-Wien_bridge_classic_osc.png


i assume R is a resistor, C is a capacitor, dots are wire connections, upside down triangles are power?(unsure).. but ive no idea what the rest is? :S

also had a quick google towards whatever an opamp is.. im from the UK and Maplins is my best bet for components i think, would this do the trick?

**broken link removed**

any help is appreciated! any newbie books you could recommend i would be happy to dedicate my time to :)

The upside-down triangle denotes a ground connection. The other things you got correctly. Just about any opamp will do, such as the LM324. The one you're looking at is probably adequate.

There is a tutorial on this site about using opams with unipolar and bipolar supplies. I suggest you read it. Your schematic does not show power supply connections, so you might find that a challenge. If you need help, just ask.
 

Hero999

Banned
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joshd963

New Member
The simplest oscillator.
How to build Reverse Bias Oscillator (circuit diagram)
8289-reverse.jpg


The inventor off the Theremin (Léon Theremin) also designed the Thing; a Soviet listening device.
Thing (listening device) - Wikipedia, the free encyclopedia

I wonder if any Theremins were bugged?

hi, ive looked at this one and the circuit looks fairly straightforward, i just got a little question or two about it if you would be so kind as to answer :D

firstly, is this correct?
8290-picvmw.jpg


secondly, im not really sure what parts i need, i tried to interpret the diagram and the paragraph but i failed, all i could find was these 2 bits... but im not even sure they would work.. (i use Maplin Electronics ? Website- Bgrade 7Inch Netbook )

Metal Film 2W Resistor - 2W Res 680R
Axial Electrolytic Capacitors - GenElect 10uF 25V

any help for an eager one? :) Thanks so far, you guys have got buckets of knowledge!


Edit: Also, wheres the thanks! button for all yer posts ;)
 
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BrownOut

Banned
Here's another fun oscillator to play with. It's simpler than the wien-bridge, but it outputs a square wave rather than a sine. The frequency can be changed by using different values of R3 and C. The frequency should be around 2*R*C. Using a huuderd or so KOhms and a hundred or so microfarads, you can slow the output enough to flash a LED. Oscillators are some of my favorite circuits. You get an output without the need to provide an input. It's like getting something for nothing.
 

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Hero999

Banned
firstly, is this correct?
8293-picvmw.jpg
Yes, that's right.

secondly, im not really sure what parts i need, i tried to interpret the diagram and the paragraph but i failed, all i could find was these 2 bits... but im not even sure they would work.. (i use Maplin Electronics ? Website- Bgrade 7Inch Netbook )

Metal Film 2W Resistor - 2W Res 680R
Axial Electrolytic Capacitors - GenElect 10uF 25V
You forgot the transistor.

BC327 QB66W

You can find which pin is which by looking at the datasheet which can be found using your favourite search engine.

The resistor is rated to 2W which is overkill (it 0.25W carbon film will do) but it's fine.

If you really want to get into electronics then I'd recommend buying multi packs of components because it works out much cheaper.

Even from Maplin you can buy a pack of 610 resistors for £6.99 which works out at just over 1p per resistor

**broken link removed**
**broken link removed**

The difference between the two packs is:

The E12 pack contains 10 of each E12 value i.e. 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82Ω, between 10Ω and 1MΩ.

The E3 pack contains 30 of each E3 value i.e. 10, 22, 47Ω between 10Ω and 1MΩ.

If you want to get into electronics I'd recommend getting the E12 kit, heck get both if you can - the E3 values are really common so it's handy having extra E3 values.

You can get similar kits of capacitors too.
**broken link removed**
**broken link removed**

Maplin's is very expensive, you can get components far cheaper online, try RS Components, Farnell and Rapid Electronics. RS and farnell tend to be more expensive than Rapid but offer free delivery so it's always good to check out all three suppliers.

Edit: Also, wheres the thanks! button for all yer posts ;)
There's no thanks button but you can give positive reputation, which sends the user a comment, by clicking on .
 

joshd963

New Member
Yes, that's right.

You forgot the transistor.

BC327 QB66W

You can find which pin is which by looking at the datasheet which can be found using your favourite search engine.

The resistor is rated to 2W which is overkill (it 0.25W carbon film will do) but it's fine.

If you really want to get into electronics then I'd recommend buying multi packs of components because it works out much cheaper.

Even from Maplin you can buy a pack of 610 resistors for £6.99 which works out at just over 1p per resistor

**broken link removed**
**broken link removed**

The difference between the two packs is:

The E12 pack contains 10 of each E12 value i.e. 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82Ω, between 10Ω and 1MΩ.

The E3 pack contains 30 of each E3 value i.e. 10, 22, 47Ω between 10Ω and 1MΩ.

If you want to get into electronics I'd recommend getting the E12 kit, heck get both if you can - the E3 values are really common so it's handy having extra E3 values.

You can get similar kits of capacitors too.
**broken link removed**
**broken link removed**

Maplin's is very expensive, you can get components far cheaper online, try RS Components, Farnell and Rapid Electronics. RS and farnell tend to be more expensive than Rapid but offer free delivery so it's always good to check out all three suppliers.


There's no thanks button but you can give positive reputation, which sends the user a comment, by clicking on .

a hero you are! so where does the transistor go on that diagram? a littlee confused! also, thanks a lot for that site, ill check it out... my birthday is coming up, i think ill get a load of electrical 'surplus' as part of it :)

Or... is the transistor the chip... i looked at the function of a transistor and it amplifies or switches a signal, so i assume its where i wrote 'chip'?

Thanks a lot!

 

audioguru

Well-Known Member
Most Helpful Member
Just about any opamp will do, such as the LM324. The one you're looking at is probably adequate.
The opamps in the LM358 (it has two opamps) are exactly the same as the opamps in the LM324 (it has four opamps).
 

Hero999

Banned
Or... is the transistor the chip... i looked at the function of a transistor and it amplifies or switches a signal, so i assume its where i wrote 'chip'?
Yes, the transistor is the chip, sorry for not making that clear.

Transistors do amplify and switch signals but the transistor in this circuit isn't being used in the conventional sense. In this circuit it's behaving like a little spark gap. The transistor has a maximum reverse holding voltage of about 7V. When the capacitor charges up past 7V the transistor suddenly breaks down and starts conducting, the capacitor discharges thorough the speaker making the cone move a bit. When the current drops below a certain level, the transistor stops conducting. The capacitor starts to charge again and the cycle repeats.

This circuit isn't very reliable and isn't the best way to make a speaker beep, it's just the simplest way to make a speaker squeak.
 

joshd963

New Member
cool! :)

is there anything more, musical?

when i say musical, im not talking about music in its controlled and delicate sense, i mean, something kind of... crazy... id like to start by making something like a squaretooth or theremin, and my ultimate goal is to make a multi osc synth, with around three oscilators and cutoff etcetera. i know that requires a tremendous amount of skill and knowledge so id like to start with a squaretooth oscillator with a potentiometer that can be output.. plug into my mixer and recorded ssomehow (doesnt matter if im clipping it to a jack lead or whatever) .. is that simple enough for a beginner?

thanks!
 

BrownOut

Banned
The sine wave oscillator ( wien-bridge ) will produce a very 'pure' sound, like the tone that's transmitted with the test pattern by TV stations. The square wave oscillator ( like the opamp multivibrator ) will produce a richer sound. Just build these oscillators and all a power amp to drive a speaker.
 

marcbarker

New Member
Can anyone post a schematic for a 'Rolf Harris' Stylophone? You can hear one of these in the David Bowie song Space Oddessy.
 
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