hi
You could get a battery holder, for say 'AA' rechargeables, make up the required voltage.

Or get a bigger guitar....

EDIT: read your PM.

The best way is use a DVM , on a current range and measure the actual current taken by the 9V.
You need to know this anyway for the battery question.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

ok.. well, another question what's an easy software for creating PCB's? Something that has most of the IC models in the default library?

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hi,

A lot of members use Eagle.

http://www.cadsoftusa.com/

free lite version:

http://www.cadsoftusa.com/freeware.htm

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

I'm checking it out, it looks a little confusing though.. when you auto-route does it actually know how to connect the power and ground to ICs 'cause in the schematic phase there are no power connection options.

I just sampled with 2 tl074's, when I auto-routed, it automatically connected both IC's grounds and VCCs together but did not connect them to the power supply.

__________________
transistance is futile...

 

hi,
I dont use Eagle.

IIRC 3v0 and atomsoft are into Eagle, they may be your best advisors.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

A 7809 has a supply current of typically 4.3mA or 8mA max.
A TL074 has a supply current of typically 5.6mA or 10mA max.
The total current is next to nothing.
You have something that is shorting the 9V supply.

__________________
Uncle $crooge

 

You're most probably right, i shouldn't get a bleeping sound there, right? (considering I'm using 1M resistors there - nothing close to a short circuit value)

__________________
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hooray!! 20A; i think there's a short...

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Can I get a "woot woot!" for the square wave output?

Now should I feed this into the PIC or should I use LM2907 to convert this to voltage then feed it to PIC's ADC?

btw the wave has 1.1 V amplitude.

Attached Images

square-output.JPG (106.2 KB, 13 views)

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Don't use an LM2907 inaccurate tachometer IC to convert frequency to a voltage. Use the micro-controller as an accurate frequency detector and indicator.

The output of the comparator should be 5V p-p not 1.1V.

__________________
Uncle $crooge

 

In the schematic, you need to click the "Invoke" button, then click the IC symbol in question. You will then get a popup asking you to specify the gates you wish to add. Select "Power". This should give you a small symbol representing the Vcc and GND for the part which you can place as you like. Don't worry that it is not visibly connected to the part on the schematic; Eagle knows what is going on and it'll be connected properly in the board editor.

Make sense?


Torben

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Curiosity was framed. Ignorance killed the cat.

 

Here is the latest version of the filter. As of now my Vpp of output signal is 1.1V . Any ideas as to why? Is there a problem with the design or my actual circuit? Will 1.1Vpp adversely affect my PIC from reading in the frequency?

Can anyone help me out with timer and RTI modules for a PIC controller (I will need RTI for frequency detection, right?) using PIC Basic Pro? I'm using a 16F877 to detect rising edges of my square wave output, start a count with first edge detected and stop on the 5th and reverse the average period to get fundamental frequency.

How do you set the timer and rti modules in PIC Basic? How do you read the timer and rti modules?

Some .bas code examples or pseudo code will be greatly appreciated.

Thanks in advance,

Attached Images

Fundamental Frequency Square Wave Generator.jpg (80.2 KB, 23 views)

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hi,
With no signal on the input, what dc voltage level is measured on the output.?

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Floating Input => VDC of Output = 2.54V
Floating Input => VAC of Output = 2.35V

Grounded Input => VDC of Output = 1.54V
Grounded Input => VAC of Output = 0V

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hi,
The grounded input, giving those output values seems odd.!
Are you sure the system isnt unstable ie; oscillating.?

Is the 1.1Vpk signal you posted earlier superimposed on the 2.54Vdc.?

You should have the Vinput connected, with the Vin set to zero, when you take these measurements...
Remember its a high input impedance opa.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/