Replies to Minipulse Plus

[golfnut]

great to see a ground or power plane on your board. should introduce more repeatability between everyones builds around the world at the very least. S

[Qiaozhi]

Although the Surf-PI and Baracuda are relatively simple designs, it appears that a great number of builders have trouble actually getting them to work.

This seems to be due to either lack of knowledge on how to logically debug a circuit, not checking component values properly and fitting the wrong parts in the wrong places, not having access to the correct equipment for setting up / tuning, or just generally not understanding how a PI works.

The Build Document is an attempt to make construction of the Minipulse Plus easier, and [hopefully] problem free. However, as they say: "Design something that any fool can use; and only a fool will use it". I hope we don't find the same issue here.

Clearly, everyone has to start their learning curve at the bottom and work up, and it's possible that building the MPP will help some people to do that. If so, then I'll be happy.

[Qiaozhi]

I have ordered some real J113 fets, in the mean time is there a suitable replacement ?

Here's a list of equivalents:
http://alltransistors.com/mosfet/crs...s=30&caps=TO92
However, I suspect just about any general purpose FET will work, as it's only being used as a switch.

The design is fairly forgiving as regards components tolerances. Although I've specified a 1% tolerance for the resistors, you should be able to use 5% without any issues. As a general rule, I only keep 1% tolerance resistors in stock. Unless you're a pile 'em high, sell 'em cheap sort of person, the odd fraction of a penny in component costs is neither here nor there. For the capacitor voltage ratings - these are also not fixed in stone. As long as the rating is greater than the maximum possible voltage across the component, then it will be ok. For caps on the 5V supplies (for example), simply choose the next higher voltage such as 10V. Of course, that doesn't mean you can't use one rated at 16V (or even 50V). As long as it will physically fit on the board, then it will be ok.

[golfnut]

Once again looks fairly tasty George.

Great to see Version Nos on the silkscreen. S

[6666]

Hi George

I guess a 2n5485 could be used as well.

[Qiaozhi]

Hi George

I guess a 2n5485 could be used as well.

As various constructors find that they don't have access to some of the specified parts, or just want to use stuff from the junk box, we can build up a separate document showing which alternative components have been tried successfully.

[Dean Sarelius]

Hi George,
I have just purchased the PCB and some other parts from Silverdog the remaining parts from Element14 here in Oz. The one part I could not purchase locally in DIP was the NE5532 so have purchased the MC33078 as a possible alternative..!

[sinclairuser]

seems that my initial reaction was wrong, and that my usual sources were crap in this aspect, ordered the board today, gonna try to use what i have in, and source parts that i dont have separately.

[Qiaozhi]

Hi George,
I have just purchased the PCB and some other parts from Silverdog the remaining parts from Element14 here in Oz. The one part I could not purchase locally in DIP was the NE5532 so have purchased the MC33078 as a possible alternative..!

The MC33078 looks like a good alternative. Please let us know how it works.

[Davor]

Hi George,
I have just purchased the PCB and some other parts from Silverdog the remaining parts from Element14 here in Oz. The one part I could not purchase locally in DIP was the NE5532 so have purchased the MC33078 as a possible alternative..!

I'm afraid this one will not do because it has PNP transistors front end which does not include a positive rail in its input voltage range.

[6666]

Dean you can get the 5532 from rs components with free postage if ordered on their website.

[Dean Sarelius]

Awesome - thanks mate - cheers

[johnandles]

here in Oz. The one part I could not purchase locally in DIP was the NE5532 so have purchased the MC33078 as a possible alternative..!

Dean, try OPA2134 available at Jaycar, here in OZ.
Cheers
John

[Dean Sarelius]

Hi John,
Just weighing up my options..have you tried the OPA2134, would you say this is a better op amp than the 5532 or do you think I should try both.?

[mickstv]

An LM4562 would be a better alternative, it has slightly lower noise than the OPA2134 or NE5532.