about noisy cricket...

[jogina111]

can MPF102 be subtituted by other FETs? I only got a general purpose one on a local electronics store... umm. I forgot the part number...

[ZeusMalt]

J201

[jogina111]

thanks. Gonna try that tomorrow..

[jogina111]

about the speakers, can the noisy cricket drive any 8ohm speaker of any size regardless of wattage?

[Seljer]

about the speakers, can the noisy cricket drive any 8ohm speaker of any size regardless of wattage?

The amp hasn't got enough power enough power to do any damage to more or less and speaker you'd hook up to it so go ahead Though you quickly discover that most speakers sound pretty bad for guitar 

You cam also hook up a 4 ohm or 16ohm speaker without ill effect.

[jogina111]

shop says they only got 1 kind of FET and its a general purpose one. Would a general purpose FET serve a replacement of the FET on the noisy cricket? Im not into buying the FET yet 'cause it costs too much and I dont like taking the chance that it wont work...

[Seljer]

The JFET in that circuit is just a buffer so generally, any JFET should work. If you can't find any FETs you can change that stage into a simple bipolar transistor buffer: observe the 4th schematic down here http://www.muzique.com/lab/buffers.htm . It might sound slightly different (mainly the FET circuit has a much higer input impedance which means it would sound brighter) but it'd perform the same function.

[jogina111]

would volume level decrease if I used the bipolar
transistor buffer? JFETs has another name for the contacts. Which is the base, emmiter and collector of JFETs?

[ZeusMalt]

Change the shop and get what you need?

[Seljer]

would volume level decrease if I used the bipolar
transistor buffer? JFETs has another name for the contacts. Which is the base, emmiter and collector of JFETs?

Not noticeably. Its just a buffer, its designed to have unity gain whatever components are used.

If this is the noisy cricket you're building http://www.beavisaudio.com/projects/NoisyCricket/Noisy_Cricket_Schematic_Smaller.gif
You want to slam this on the front of it instead of the JFET stage: http://www.muzique.com/images/buff5.gif

The 3k3 resistor the the capacitor marked C2 in the amp's schematic remain the same, you just change the transistor and add the extra resistor and capacitor at the intput.

[jogina111]

I dont get it. Should I replace the caps and resistors or just add them at the buffer stage?can you show me a drawing on how to final schamatic will look like? Sorry, still a noob at electronics

[artifus]

http://postimage.org/image/62td62e0t/

[jogina111]

umm how do I position the caps? I got many electrolytic caps and it would be a waste if I wouldnt use them.

[artifus]

http://www.beavisaudio.com/techpages/SchematicToReality/

[Seljer]

umm how do I position the caps? I got many electrolytic caps and it would be a waste if I wouldnt use them.

On electrolytic capacitors one side is usually denoted with a strip of - symbols (and the pin on that side is shorter than the other one) or just a simple line. That side is the negative side, so that leaves the other one to be positive. Just match up the orientation to the whats shown on the schematic.