Sine wave signal generator

[Napalm Llama]

Hi. I've been tinkering with the odd electronics project for a few
years now, but I'm stumped on this one. I've constructed this circuit:

http://www.yellowmackerel.co.uk/circuit.gif
(Originally from here: http://www.4qdtec.com/singen.html , but the
server seems to be down.)

....except I'm using an NE5534AP op-amp instead of the 6-transitor
circuit (as the accompanying text said I could).

But it isn't working. All I get is a low tone that sounds suspiciously
like 50Hz. I've checked the power supply circuit with my multimeter
and the output seems to be perfect, but I can't check how much ripple
there is because I don't have an oscilloscope.

The dual-ganged potentiometer seems to alter the volume instead of the
tone, and the rotary switch doesn't really do much at all. The op-amp
itself just gets worryingly hot.

I've just discovered that if I only connect 0v to the IC and put my
thumb across the "lower" pot in the circuit, moving it does alter the
tone a little.

I don't know if this is enough to go on, but please help in any way you
can - I've spent a fair bit of money on this project and I don't know
why it isn't working...

 

[Dan H]

Napalm Llama wrote:

Hi. I've been tinkering with the odd electronics project for a few
years now, but I'm stumped on this one. I've constructed this circuit:

http://www.yellowmackerel.co.uk/circuit.gif
(Originally from here: http://www.4qdtec.com/singen.html , but the
server seems to be down.)

...except I'm using an NE5534AP op-amp instead of the 6-transitor
circuit (as the accompanying text said I could).

But it isn't working. All I get is a low tone that sounds suspiciously
like 50Hz. I've checked the power supply circuit with my multimeter
and the output seems to be perfect, but I can't check how much ripple
there is because I don't have an oscilloscope.

The dual-ganged potentiometer seems to alter the volume instead of the
tone, and the rotary switch doesn't really do much at all. The op-amp
itself just gets worryingly hot.

You need to show the actual circuit you are using not the circuit you
have based it on

dan

I've just discovered that if I only connect 0v to the IC and put my
thumb across the "lower" pot in the circuit, moving it does alter the
tone a little.

I don't know if this is enough to go on, but please help in any way you
can - I've spent a fair bit of money on this project and I don't know
why it isn't working...

 

[Tom Lloyd]

Hmm, perhaps a better question to ask would be, "How should I actually
substitute an NE3455AP (http://www.ampslab.com/PDF/ne5534p.pdf) into
the circuit I posted?

From the original webpage:
"The 6 transistor circuit is, in effect, an op-amp and there is no reason you can't simply use an op-amp. This circuit pre-dates op-amps but the principles haven't changed."

It's all obvious, except for the inputs - there appears to be only one
in the schematic (at the base of the leftmost transistor). I tried
wiring that up to my op-amp on pin 2 (inverting input) - and then 0v on
pin3 (non-inverting) - but like I said, it didn't do anything except
get hot.

 

[jasen]

On 2006-07-08, Tom Lloyd <napalmllama@gmail.com> wrote:

Hmm, perhaps a better question to ask would be, "How should I actually
substitute an NE3455AP (http://www.ampslab.com/PDF/ne5534p.pdf) into
the circuit I posted?

Th1 is what ? (some sort of thermistor?)

input is from the switch (non-inverting input)
and from the thermistor (inverting input)
op-amp output is to the point labeled "out"

don't expect to drive a loudspeaker or headphones
from the output terminal. it'll need some sort of
amplifier to do that.

keep switch, capacitors, potemtiometer, the 1K resistors, thermistor,
and 100 ohm resistor the other parts are replaced by the op-amp.

Bye.
Jasen