Paradise Builders

[RCruz]

thank you... will do

[beetle]

Originally Posted by FdW

Show me (one more time) a full set of voltages test-points, Vin and Vout. Also would you measure all Vak(LED's) in the CVS and the CCS and, V(be) power and small signal transistors. It seems that the PSU is working but I want to know (at a philosophical level) why it is (as it is). This will make it easier to help other people.

P.s. The MJE's should be good, also the TIP's and the D44/D45's, but the D44/D45 where my first choice

Ok here we go:

TP101: 19.93V
TP102: 18.23V
TP103: 23.83V
TP104: 562mV
V(in)=29.88V@174mA

V(L110): 1.90V
V(L111): 1.90V
V(L112): 1.91V


V(BE Q101): 607mV
V(BE Q102): 347mV
V(BE Q103): 7.34V
V(BE Q104): 1.24V



TP201: -19.68V
TP202: -18.21V
TP203: -23.71V
TP204: -571mV
V(in)=-29.84V@151mA

[Benedetto]

Originally Posted by FdW

If not what?

The resistors wont be changed,
is there a known issue ?

[FdW]

Originally Posted by FdW

If not what?

A picture tells more than a thousand words, so here is a picture.

The voltage (Vgs) of the mosfet is about 4V, the current that is (selected by me) wanted in the Jfet is 1mA. The picture shows resistor values for popular Jfet's to accomplice this (1mA). What can be seen is that, in fact, the J310 is the most marginal of the shown Jfet's (it is just capable of supplying the wanted 1mA).

Any of the Jfet's shown can be used (and I am sure there are many more) but you need to change the resistor value and indicated.

[Benedetto]

Ive asked this rather stupid question because in the GB mine,
and many other sets delivered, contained only the alternative
fets....

[FdW]

Originally Posted by beetle

Ok here we go:

TP101: 19.93V
TP102: 18.23V
TP103: 23.83V
TP104: 562mV
V(in)=29.88V@174mA

V(L110): 1.90V
V(L111): 1.90V
V(L112): 1.91V


V(BE Q101): 607mV
V(BE Q102): 347mV
V(BE Q103): 7.34V
V(BE Q104): 1.24V



TP201: -19.68V
TP202: -18.21V
TP203: -23.71V
TP204: -571mV
V(in)=-29.84V@151mA

I will, tonight, have a look at them. At first glance it seems the V(be Q102) is a bit low, and that this is debit of the current unbalance.

[dubai2000]

I am new to transistor matching so the question might be silly, but would a device such as the following be useful?

Found at Reichelt: ATLAS DCA55

Your feedback will be appreciated - thx.

dubai2000

[hesener]

Originally Posted by dubai2000

I am new to transistor matching so the question might be silly, but would a device such as the following be useful?

Found at Reichelt: ATLAS DCA55

Your feedback will be appreciated - thx.

dubai2000

checked it out - very nice. I am tempted to buy one myself.... It will do not only bipolar but also JFETs and other stuff....

In fact, matchign the gain devices makes a hell of a difference for audio amplifiers, as compared to just sticking in whatever comes out of the bag first. Many higher-performance (non-feedback) circuits really only work with selected / matched devices.

[Joachim Gerhard]

I use it all the time. Buy it.

[Salas]

Watch only that the Atlas does shove much Ib with a CCS inside, so the reported Vbe will be more than usual in circuit. But if they match @ that condition they do follow with other bias states more or less. Good thing is it tests LEDS in a much more real life 3.5mA than the proverbial 1mA that meters do. Many don't even put out enough voltage to light an LED to start with. What Vf matches on my Atlas matches on my F87V too, but when looking to use them as voltage ref you need to know not only matching but Vf @ bias current too. Ah, and Atlas is a battery hog.