bf245b transistor orientation/chip protection

chokesrule

Member
2010-06-25 4:24 pm
Hi, I am building this sp/dif buffer as suggested on the Lampizator site the schematic is on the page
CD Transport Digi-Lampizator
[IMGDEAD]http://http://www.lampizator.eu/digilampizator/JFET-buffer.pdf[/IMGDEAD]
It is a simple question :do I have the flat side of the "D" facing the signal wire ????? I take it the sp/dif signal enters the transistor on the centre pin.....It is not that I am too lazy to experiment , I am just worried wrong orientation would blow the signal generator chip or something nasty and the Quad 99 I am using is made of very very flimsy parts , I think it would be hard to repair..Thanks Alan...
ps if I am worried about blowing chips can you protect them by using a diode in series along the signal wire??
 

chokesrule

Member
2010-06-25 4:24 pm
cannot figure out how to put a picture on here

the link has not worked hopefully the picture of the schematic will appear here
[IMGDEAD]http://www.lampizator.eu/digilampizator/CD%20Transport%20Digi-Lampizator.html[/IMGDEAD]

you will have to scroll to the bottom of the page for the diagram
 

Tfan69

Member
2009-05-30 2:44 pm
hello,
this is the pin configuration of the bf245b, signal enters in G pin, which is at bottom looking at D
 

Attachments

  • piedinatura_bf245.jpg
    piedinatura_bf245.jpg
    10.6 KB · Views: 35

chokesrule

Member
2010-06-25 4:24 pm
still confused

Tfan69....does the power come in on the "s" or "d" pin then??????.....sorry for being so thick...

Luke .....I have no idea I was just going to connect it and see what happens....I do not even know what spdif generating chip I have ...all I know is is that a stock quad 99 is a very very poor affair indeed and needs all the help it can get
 

chokesrule

Member
2010-06-25 4:24 pm
0.3v dc

Hi, Tfan...I have built the buffer and am running it off a 9volt battery for a minute...its built as a external unit and plugs into the rear digital output socket on the player....and outputs to an external dac.... SO ....all rca grounds /battery ground and resistor grounds share the same rail........Before I plugged into the player , I put a multimeter on the output hot pin and found it is outputing 0.3volts DC before any sp/dif signal is applied....I was suprised to see the DC as I thought the 10 uf capacitor was supposed to block it....I have double checked everything and cannot see how I have varied from the diagram....so is this an acceptable amount of dc to be going to the dac or have I indeed messed up??? I have not plugged the unit in as I am worried about the dc....is my grounding right?
 
10uf

its definately a 10uf non polar just a cheap brand...i have left the thing powered and now when I read the pin i see....0.02volts dc....could this be evidence of the so called "burn in" of a electrolytic???? is 0.02v safe for the dac? I will raid my parts bin attach a resistor like you said .....see what happens