Re: Amplifier Schematic

On 19 Jan 2006 12:01:32 -0800, "James" <JamesAnthonyJoyce@xxxxxxxxx>
wrote:

>Hello All,
>
>Could anyone here direct me to a schematic for a high current, low
>voltage signal amplifier? I need an input Voltage of no greater than
>8V, and an output current of about 20A.

Do you need it to be linear? Do you need the output current to be
either 0 A or 20 A, or all possible values in between?

>Sone Voltage gain is
>acceptable. The wave to amplify is a square wave.

If the input is always a square wave, best is to use a switching
amplifier, as you were using. This is why I asked about linearity. You
don't seem to need linearity.

>I know this is a tall
>order, but I have an existing H-bridge circuit that is acting as a
>square wave amplifier now, and I don't want to use it for too long, as
>the signal is attenuated at low Ohm loads.

I guess you mean that, at low ohmic loads, you don't have enough load
current. That might be due to:
- Insufficient supply voltage for a given load resistance.
- Excessive load resistance for a given supply voltage.
- Excessive switch resistance (make sure you use low resistance
MOSFETs, and that Vgs is high enough).

1, 2 or 4 switches (MOSFETs / BJTs, ..) is your best structure, if the
input is always a square wave. A linear amplifier won't help.

>I have at my disposal
>several high current rated MOSFETs, and all types of standard
>resistors, inductors, capacitors, etc. Thanks for the help.


.

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