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Hmmm, ?not much found when I Googled the first time but I guess I chose my keywords better the second time and found this which is not too complicated
and looks pretty good. ?It can be scaled according to the size of the speaker.?

Cheers?


Michael VE3WMB?

Google speaker hole template

there are lots of patterns

i advise you to use the simplest. Eacc. Ew hole is a chnace to ruin the wwork

Not wanting to re-invent the wheel ... ?has anyone come up with a template for drilling holes in an enclosure for a 2 to 3 inch speaker ?
I was hoping to find something that I could print out and tape to the outside of the enclosure to use as a guide for drilling sound
holes in a regular pattern for a 3 inch speaker.?

If not, I will see what I can come up with and I will post to the group.?

Cheers

Michael VE3WMB?

if you are using Raduino it is a 10K Lin not a 100k, and remember to buy a "good" pot not the cheap "Mexico" otherwise a few resistor and if you are going to have more "punch" in modulation you needed 22pf+4,7pf to replace a 47pf?

RTFM = read that fu..... manual :-)

sorry this is the link for the box

I have this one. Enough room and the nice tilting bar feature. You will have to drill holes for the speaker. You may use different panels as the fron and rear are detachable. They are only with a sliding panel.
I suggest you shield it with this tape or something like that?

The datasheet says an absolute max of Vcc+0.5v on any IO pin. ?So if the Raduino power is down (even momentarily), tying the Bitx40's 78L05 directly to the Nano's A0 will blow the Nano, even if the 78L05 never exceeds 5v.

John Backo,

Most of your post seems to be in regard to this excerpt from one of my previous posts: "You either get a 0 or a 1 back when you read a pin with digitalRead(). ?If the voltage at the pin happens to be midrange the result is indeterminate, but the result will be either a 1 or a 0." ? ?Exactly what did I say that is "not quite"?

Regarding the need for an external reference, on page 311 of the ATmega328P datasheet previously referenced, it states: ?"VREF can be selected as either AVCC, internal 1.1V reference, or external AREF pin." ?So no need to tie the AREF pin to anything if you set up the ADC properly. ?At any rate, AREF is only used for the ADC, for an analogRead(). ?When doing a digitalRead() the AREF pin has nothing to do with it. ?In Allards code, A0 is read as a digital pin.

Regarding threshold voltages, figures 33.25 and 33.26 on pages 391,392 of the datasheet show that you are correct, threshold is centered roughly on half of Vcc, or 2.5v in our case. ?(As I read the graphs, for a Vcc of 5v the threshold will be somewhere between 2.1 and 2.7 volts. ?Reading a pin that lies between 2.1v and 2.7v might give a 0 or a 1.) ? That's quite common. ?Also common is to have the input threshold down around 1.2 or 1.5v to be compatible with TTL and low voltage CMOS devices, that's what I was thinking (without looking at the datasheet) when I stated ? ?"I'd expect the threshold on the nano to be somewhere between 1 and 2 volts". ?A 2.7v max on the threshold suggests that reading 1's from the 3.3v Si5351's I2C bus could be a bit dicey, especially if the speed were cranked up some.

Jerry, KE7ER

Well, the last message mixed metaphors a bit and should be thought through.

If A0 is an analog pin (which it is by default), then the AREF is divided into 1024 parts and the measured signal is reported as a percentage of that. If A0 is redefined as a digital pin, then the signal must be a 0 or a 1. There is a grey zone at about AREF/2 which the uC cannot decipher. That is the area to be avoided in a digital configuration.

So, if the program is to provide a positive shift (one of two outputs based on one of two inputs), then A0 (or any other pin) must be designated as a digital pin, and a sure zero or one region must be insured for the signal. I have not examined the code to see what the designation of A0 is. But it must be digital for this application. It looks like the signal is sometimes in the grey zone and that is what is causing the basic behavior. Every uC will give a slightly different response to this, so it may be a problem for some and not for others.

The idea of NOT providing a direct more or less unlimited voltage/current source to any pin (except those designated as Vcc) is a good one.
Suppose there is a VR connected directly to a pin and it is powered up but the uC is not. Then the uC will attempt to power up, using the connected pin as a voltage source. If it can find a ground, it will power up and the current draw will easily exceed the 40 ma. limit of the pin.
So don't connect a VR directly to any of the uC pins except Vcc. And if the voltage source is more than ~5.5v, that will guarantee destruction of the uC, even at the Vcc pin. The raduino provides a on-board VR to handle this problem; but use caution anyway. Think about it. Trace the circuit and be sure of what you are doing. There should never be more than 6v maximum on any pin of an Atmel (or PIC) uC. There should never be more than 3.5v on those designated as 3.3v devices.

john
AD5YE

Not quite, Jerry.

"I've put the 10k pull-down register at the "A0" and maybe the problem seems to be fixed now. This issue caused by the threshold problem?"

The issue is a bit complex, but the solution is simple.

First, the value of Vcc is the voltage applied to the device. Some 5v VRs will be 4.95v; others will be 5.6v or so.
Theoretically, Vcc is 5v and the transition from 0 to 1 as sensed by the uC is 2.5v. But actually it may be different.
Is it really 2.5v? Or is it 2.71v? Or 2.42v? You don't know and cannot be sure. Especially if AREF is left floating.
The spec says that the total voltage applied anywhere to the device is Vcc + 0.5v. The Atmel spec for Vcc is 5.5v.
I have run them well on 5.7v or so, but anything over that blows them up...

First, connect AREF to Vcc so that the maximum voltage sensed by the pin is that of Vcc. Then, realize that there is no particular point of 0-1
transition; there is a "grey" zone which is neither a 0 nor a 1, usually from 2.4 to 2.7v if AREF is nominally 5v.

What Hidehiko found is that connecting a DVM was enough to move the signal away from the grey zone and the uC was able
to interpret the signal. His solution is correct -- one must insure that the A0 signal is either less than 2v or more that 4v PROVIDED it
does not exceed AREF by 0.5v. The current draw is taken care of internally and really doesn't matter whether it is potentially small or large
externally. What matters is voltage. The usual solution is to put a 10k resistor between the pin and Vcc. Then a high is always at Vcc
(which is also AREF). Then the problem becomes a matter of insuring that a proper zero is applied; the resistor will limit the current automatically. If the external sense voltage is greater than AREF, then a voltage divider must be provided which will give a proper range
to the uC. Note that pull-up and pull-down internal resistors apply to digital IO, not an analog designated pin. One can designate A0 as digital,
but it must be specifically done in the firmware.

The key here is that there must be a sure zero region and a sure one region. One must avoid the grey middle as the uC cannot make a
decision if the signal is there.

john
AD5YE

Sockets are good when you need them, but otherwise they are just dozens of extra potential points of failure. ?Especially for somebody operating portable at the beach, the slightly corrosive salt air could tarnish those connections.. ?I'd like to see the Si5351 on the Bitx40 board so it's just a few wires from Bitx40 to the processor+display of our choosing, no need for a 30 pin connection from Nano to Raduino. ?The Nano is just one of the many processors that we might want to use with the Bitx40.

Here's the datasheet for the processor used on the Nano: ?
On page 365, they spec an absolute maximum of voltage on an IO pin of VCC+0.5, if VCC is at zero then the maximum voltage is 0.5v. ?Beyond that, you may damage the device.
They also spec an absolute maximum current into that IO pin of 40ma.

I was cautioning against hooking up the 78L05 directly to a Nano IO pin because we would be exceeding both of these specs by quite a bit if we have the Bitx40 powered up and the Raduino not powered up, or perhaps not yet powered up due to a few milliseconds delay in charging up a cap somewhere, or have a failed regulator on the Raduino, or a flaky connector somewhere.. ?You will blow an IO pin unless you pay attention to this sort of thing.

This case is a bit unusual in that we would have been driving that IO pin from a voltage source capable of hundreds of ma (the 78L05 datasheet says at least 100ma while holding it within spec near 5v, but it could give much more). ?If it's just a regular signal going into the Nano from some peripheral chip, they generally don't drive more than 10ma into a dead short to gound, and the Nano IO pins can live through that. ?With that 10k series resistor that Allard recommends in his notes between the 78L05 and the Nano's A0, the current is limited to 5v/10k = 0.5ma, which is far less than the Nano IO pin's 40ma max, so most of the 5 volts from the 78L05 will be across the resistor, the voltage from A0 to ground would be just a fraction of a volt.?

Jack wrote:
> ?Admittedly, my memory's not what it used to be, but I don't remember anyone
> ?blowing an Nano I/O pin. I'm sure there have been some who somehow
> ?connected 12V directly to an input pin but, to me, that's a $3 lesson that they needed to pay.?

Yep I blew up one as well when I had it just wired up and laying on the workbench and I just repaired another one with the same problem. It is only $3 but I sure would like to know the thought process of not putting it in a socket. I know it probably saved a few cents but when I was cutting out the original one it sure didn't seem to be worth it at the time.
Jeff
N9ARZ

Back in January I experienced a short with one of the loose wires and the metal heatsink. Jerry knew how to fix the rough tuning that resulted from the short. The A6 tuning pin was conducting current instead of sencing input. The solution was to change to A7 for tuining, both the wiring and code. There might have been 3 more who had something similar happen. It also wiped the Raduino code, just left it running blink. It,s all back there if you want to look for it.