Serial communication problem.

[CDRIVE]

2N2222 (fT) = 250MHz.
2N2222A (fT)= 300MHz
BC547 (fT)= 300MHz

Are you sure you had the pinout correct?

Chris

BTW: Irma left but not before it uprooted one of my large Ficus trees. It's now laying across my house and shop that's attached to my screen room and the back of my house.

I tell you this because my replies may be sporadic.

Chris

 

[Harald Kapp]

Good to hear you are unharmed

 

[HellasTechn]

BTW: Irma left but not before it uprooted one of my large Ficus trees. It's now laying across my house and shop that's attached to my screen room and the back of my house.

I tell you this because my replies may be sporadic.

I do not understand

 

[HellasTechn]

Are you sure you had the pinout correct?

Yes i am positive. I have them on a "mount" so i justremoved the 2n2222 and put the bc547 the same direction.
I also made sure the transistors where well sit in place.

 

[Harald Kapp]

I do not understand

Hurricane Irma. You noticed where Chris lives?

 

[HellasTechn]

Ho my god... I was not aware that the hurricane was called irma. Actually it didnt even crossed my mind that he may have been affected.

My best wishes to you sir Chris !

 

[CDRIVE]

Thanks for the good wishes mates. They're appreciated very much.
Constantine, I don't have an answer for you. I would think that a 2N2222A would handle your baud rate. Perhaps someone else has a clue? What values are your Collector and Base resistors?

Chris

 

[HellasTechn]

10K each.
P.S. It's fine as long as it works !

 

[CDRIVE]

I believe that reducing those values to 1KΩ will reduce switching time.

Chris

 

[BobK]

Yes i am positive. I have them on a "mount" so i justremoved the 2n2222 and put the bc547 the same direction.
I also made sure the transistors where well sit in place.

Are you sure you have a 2N2222?

The ones in TO92 cases are generally PN2222, wtih pinout EBC. I don't know if there even exists a 2N2222 in TO92. They cone in an old metal can.

The BC547 is CBE.

Bob

 

[HellasTechn]

Now that is strange. I have the PCB connected as shown in picture #61. Now with the 2n2222 (TO-92) (they are actually marked 2n2222) my picaxe can not read the ttl signal while with the BC547 in the bace (face same direction as 2n2222) meaning collector to ground and emitter to +5V then the picaxe can read ttl correctly.

How can this be explained ?

 

[BobK]

Okay, a little more research find that there are 3 varieties.

2N2222 metal can
P2N2222 TO-92 euro pinout CBE
PN2222 TO-92 american pinout EBC

You might want to try reversing the 2N2222 ones to see if it works.

Bob

 

[CDRIVE]

Now there's a surprise. I had no idea there is a European version.

Personally, I like EBC.

Chris

 

[HellasTechn]

The BC547 i have are CBE and the 2N2222A are EBC
I had no idea about different versions either Though i have seen the TO-18 one.

 

[CDRIVE]

There's quite a few versions of this Component Tester. For the price they're worth their weight in gold.

Chris

 

[HellasTechn]

Yes i do have one. It actually confirms that the BC547 i have are CBE and the 2N2222A are EBC.

Today i found some time to play with this project and i discovered that the picaxe does not understand half of the data i send to it. So indeed i will need to reverse the BC547 to correct direction so that emitter goes to ground and collector to Vcc through the 10K resistor. If that doesnt work then i will try a 1K base resistor instead of 10K.

 

[HellasTechn]

I have builded the circuit exactly as pictured in post #61 and used the Oscope...

The base through the 10k resistor was connected to the 5V 1Khz scope's output. The resaults are pictured below.

What i found is a perfectly shaped 5V square pulse 180 deg inverted compared to the input square wave signal.
I got the exact same output no matter if i had the emitter tied to ground or tied to VCC.

same outcome with the 2n2222 and BC547 transistors.

How can that be explained ? maybe when i tie the emitter to vcc and collector to gnd, the transistor works in "reverse-active" mode ?
like explained here ? https://learn.sparkfun.com/tutorials/transistors

Picture 1 = 2n2222 emitter to gnd and collector to vcc
Picture 2 = 2n2222 emitter to vcc and collector to gnd
Picture 3 = bc547 emitter to gnd and emitter to vcc
Picture 4 = bc547 emitter to vcc and vollector to gnd.

 

[CDRIVE]

I keep thinking that Rod Serling is hiding in the shadows!
Is your scope a dual trace? If so please post the input signal vs the output signal.

Chris

 

[HellasTechn]

I will right now. I will post back in 5 minutes.

 

[HellasTechn]

Ok. theese are from the bc547.

Picture 1 = with collector to gnd
Picture 2 = with emitter to gnd.

Channel 1 = output signal
Channel 2 = input signal