Software signal generator ...

[DeepCut]

Hi.

i want to get more power out of a software signal generator that outputs through the soundcard.

A couple of questions :

1. Would i just use a transistor (2N3055 ?) hooked up to a DC power supply ?

2. Would there be any frequency interference from the DC PSU ?

Thanks,
Gary.

[poynt99]

Hi.

i want to get more power out of a software signal generator that outputs through the soundcard.

A couple of questions :

1. Would i just use a transistor (2N3055 ?) hooked up to a DC power supply ?

2. Would there be any frequency interference from the DC PSU ?

Thanks,
Gary.

That will not work, at least not easily.

The simplest thing for you to do imo would be to find and audio amplifier of some sort...any type with an input for audio sources will do, depending on how much power you want out.

Run the soundcard output straight into the audio amplifier input, and start with the soundcard output level almost at zero. You can incorporate an attenuator pot if you wish to cut the level down, but it's most likely not necessary.

.99

[DeepCut]

Thanks poynt,

i tried that with a mono mic preamp i had lying around.

The meter sees the voltage going high/low so it's working.

But i want to use my DC PSU so i know the voltage/current going in and use the full range of the PSU.

I thought i could modify a spare Bedini circuit i had, since it does exatly what i need, a small trigger voltage causing the larger PSU voltage to flow.

But i can't seem to be able to do it


Gary.

[poynt99]

If you are looking to be able to monitor how much power is being used from a power supply, then you might be interested in a small amplifier module such as this one on ebay:

http://cgi.ebay.ca/Low-Voltage-Audio-Amplifier-Module-Based-NJM386-/400176660727?pt=LH_DefaultDomain_0&hash=item5d2c6340f7

Might be just what you require

.99

[mscoffman]

@deepcut,

I agree with poynt99...It would be best to get some audio amplification
before driving a 2n3055 NPN power transistor base circuit. A "standard
audio line" such as the output of a computer is meant for driving earphones
or (stereo) amplifier inputs.

"Standard audio line" has the 0db point at 1 volt peak-to-peak into 600ohms
where the center voltage is ground/0volts. So I would expect a computer
with it's volume set 1/2 way up to be issuing standard audio line output power.
A standard audio line is what a TV set might have when it knows it is going to
be driving a amplifier to a speaker. While standard line level is what the amplifier
input will expect to see. Audio speakers have relatively low impedance like 4 to 64
ohms so they are power devices.

The standard line may be just able to drive the 2n3055 if you use an audio isolation
transformer. - Like the phone line transformer from an old obsolete modem card.
Those are often primary 600ohms:600ohms secondary that is 1:to:1. Obviously a
2n3055 is going to produce a unipolar (digital) signal of swing +V to 0. An audio
amp preserves the +V to -V swing of the signal. Use a transformer or blocking
capacitor to get the signal polarity of AC signal you want.

Any out-of-band-noise can be filtered with a small (filter) cap.

:S:MarkSCoffman