Airforce Condor Forsale

The beginning has been made ...

Just another blog was born ...

Well, now it has been quite irritated herself somehow to start a little blog. It is after all not everything around it. But instead of you, dear readers, with minor details a la Twitter terror over what I have to tell just cook or that again, nothing comes on TV, I try to love this blog more or less to keep professional and much more on small achievements to report findings and news on our / my everyday life too much engineered to enrich in the hope of all of us know anyway. Forgive me this banter. In my next life I'll doctor promised your John

Frozen Daiquiri Mix Buckets

protection measures for the power amplifier circuit with BJTs

Start Blog ppdriver
experimental circuit with BJTs

protection measures for the power amplifier in the power amplifier

In a booster, it can happen that a defective output tube work. To other tubes and the amplifier to protect themselves, protective measures must be taken. These are described here.

grid emission or insulation failure may cause a small grid current. In conventional circuits with Gitterableitwiderstand calls this current a voltage drop on Gitterableitwiderstand, which counteracts the negative bias. As a result, the plate current swings high at first unnoticed, leading to the destruction of the tube and the apparatus. This is one of the most common causes of errors in conventional tube radios and amplifiers and is especially happy after overloading the output tube. The galvanic Coupling avoids this known. The grid would have to complete the rest of the current Katodenfolgers take in order to distort the lattice strain dangerous. In this respect, the electrically to the output tube (s) coupled Katodenfolger a very effective measure against this effect.

course of Katodenfolger can even be dangerous when he has a lattice Katodeschluss or even worse, makes a rollover to the anode. The latter is quite possible if the anode is connected to the anode of the Katodenfolgers pentode. The grid of output tube may be destroyed. To counteract this helps a resistor, which is comparatively small signal not should be recognized as a series resistance. With push-pull circuits, which can very elegantly realized with a common protection for resistance in both push-pull working Katodenfolger. If this resistance is correspondingly high resistance or even a power source, so you get a FREE anode coupled differential amplifier .

A very hot potato is a grid-Katodenschluss in an output tube. This also applies to parallel output tubes. The current flow may not raise enough from the line fuse, which in case of failure of the negative bias may still be possible. A protection circuit that also in case of negative bias or a grid in an output tube Katodenschluss appeals should therefore be missing in any power amplifier. How is the 6 x EL34 amp is made, the diagram shows

Here comes again the galvanically coupled Katodenfolger as rescuers into the game. Without taking into account the need for coupling caps, it makes it relatively low-Sense 56KΩ resistors of the current node P (P = Protect) to lead. If the current at node P has a minimum value, here about 1mA, open collector off the stage in the amplifier existing STBY and anode voltage delay circuit immediately on standby, ie anode-energized when an error in the final stage occurs. The electro-mechanical analogy, would be a relay which drops at low 1mA.

A few additional 0.8 mm holes and the circuit is already accommodated on the board of the amplifier.

This work is licensed under a Creative Commons Attribution
-Noncommercial-No Derivative Works 2.0 United States License .

Chapstick Wedding Gift

Differenzverstaerker experimental

Please read the blog start first. This blog explains the 'common mode feedback' aspect in the circuit. A simple BJT breadboard circuit is build and some measurements are taken. The 'common mode feedback' makes the output floating X3 X4 and creates an 'anode coupled' amp differential characteristic for Q3 Q4.

the Start Blog please read this first!

To interconnection of katodengekoppeltem - understand and anodengekoppeltem differential amplifier, I made once the following experimental circuit with bipolar transistors :

Like that you can easily keep track of how and check. With the below given values one obtains a gain of 20dB. The operating voltage VCC = 24VDC allows line level at the outputs X3 and X4.

Resistor
R01 = R02 = 2K2Ω
2K2Ω
R03 = R04 = 1MW
6K8Ω
R05 = R06 = 1MW
820Ω R07 = 820Ω

R08 = R09 = 100ppm 100ppm

R10 = R11 = 200Ω 200Ω

R12 3K9Ω
= R13 = R14 = 100ppm 100ppm

R15 = R16 = 100ppm
2K2Ω
R17 = R18 = 100ppm 2K2Ω

R19 = 4K7Ω

Capacitors: C1 = 47uF 63VDC
positive terminal to Vcc
C2 = 1μF 63VDC negative pole connected to X1
C3 = 1μF 63VDC negative to X2
C4 = 1μF 63VDC positive pole at Q1
C5 = 1μF 63VDC positive at Q2
C6 = 100uF 25VDC negative to GND
C7 = 47uF 16VDC negative at X3
C8 = 47uF 16VDC negative on X4
C9 = 220μF 10VDC negative to GND

diodes:
D1 = 1N4148
D2 = 1N4148

transistors:
Q1 = BC547C
Q2 = BC547C
Q3 = BC547C
Q4 = BC547C

Short functional description of the components in detail:
Resistor
R1, R2 _Arbeitswiderstände for the difference amplifier transistors Q1, Q2.
R10, R11 _Stromgegenkopplungswiderstände for the transistors Q1, Q2. By their resistance to the working relationship resistors the gain rate, here is 20dB festegelgt. Hold the working slope of Q3, Q4 constant.
R16, R17 _Arbeitswiderstände for the difference amplifier transistors Q3 Q4.
R3, R5, R15, R19 _laden on the coupling capacitors and pull the connectors X1, X2, X3, X4 moderately high signal to GND.
R4, R12, R19 _teilen the operating voltage Vcc voltages in the operating point of the differential amplifier.
R8, R9 _Entkoppeln comparatively small signal, the bases of the DC voltage on C6. R13, 14 _Entkoppeln comparatively small signal, the bases of the DC at C9.
R6, R7 _Überstrom and vibration protection resistors to the bases of Q1, Q2.

Capacitors: C1
_Betriebsspannungsblock
C2, C3, C7, C8 _Koppelkondensatoren
C6 _Referenzspannungsblock
C9 _Referenzspannungsblock
C4 _Koppelkondensator combines moderately small signal collector of Q1 with a base of Q3.
C5 _Koppelkondensator combines moderately small signal collector of Q2 base of Q4.

diodes:
D1, D2 _verhindert the Zenern the base-emitter diode of Q1, Q2.

transistors:
Q1, Q2 _This differential amplifier pair is defined as follows in analogy to the differential amplifier katodengekoppelten in the text.
Q3, Q4 _This differential amplifier pair is defined as follows in analogy to anode coupled differential amplifier in the text.

A few basic, general observations on the differential amplifier.
A differential amplifier is characterized in that its differential gain is greater than its sum gain. Ideally, there will only differential gain. This is achieved by coupling two differential amplifier branches. The sum signal may, ideally, cause any change in current in the differential amplifier branches can. This requires, if the difference is not complementary amplifier paths are built next to the two tube or transistor stages yet, any kind , "Power Supply". This is the power of willing in accordance to the two levels of control, distributed. Small-signal standard depends on the symmetry of the output voltage to GND by the symmetry of the load resistors, but not on whether electrically equivalent transistors or tubes in the two branches are used. The only plays a role when the real "current source" too low internal resistance gets.

The complementary circuit technology enables the coupling of both branches of the differential amplifier without the separate "Power Supply". A complementary differential amplifier is used for example when UVB ; Q10 and Q2 form its complementary differential amplifier branches, here in the asymmetrical design. The interconnection

be the anode and katodengekoppelten differential amplifier,
disappeared following the Gleichtaktverkopplung *
the separate "power sources", the sun, would be for both differential amplifier alone, are needed.

measurements on the circuit:
large signal

The figure I have registered with the digital multimeter (R = 10MΩ) measured dc voltages.


For maximum headroom, should it ever fall ≈ ¼ of the operating voltage of the transistors and resistors work. Accordingly, the divider resistors R4, R12 and R19 are sized. If R11 is short, lying on the collector of Q1 and the collector of Q2 20VDC 16VDC. The current gain of the transistors is B ≈ 500th

small signal

rEasym measurement of the input resistance of the circuit:
5:00 input signal 1KHz sine of-20dBu, 200mVpp corresponding to X1, X2 it short. Output voltage at X3, X4 measure. -14dBu, so 400mVpp debug via resistance at X1, resistance value for the same output voltage. The
be considered resistance value is 56KΩ. The same value is obtained for X2 at short circuit of X1.
NAV
rEasym = R3 II R9 II hfe x (R10 + 1 / s)
rEasym = 1MW II 100ppm II 500 x (200Ω + 15Ω)
rEasym = 1MW II 100ppm II 108KΩ = 49KΩ
The input resistance rEasym is ≈ 50KΩ .

Tip:
The input capacity is at its lowest when the two differential amplifier operate asymmetrically and is used in phase to the input output lying. In plain English, if X1 is input to X2 and X3 and X4 grounded used as an output. The signal emitter follower → Basic Amplifier (with local negative feedback) → emitter follower provides a very fast broadband and amplifier topology. It is therefore used in a complementary form of the Universal video board.

measurement of the output resistance of the circuit
6.oo output resistor between the emitters of Q3 and Q4 ree:
sine of 1kHz-46dBu to feed at the entrance. Load resistor at the output X3-X4 Sun debug that the level of breaks in half. The ausgeürpfte ree resistance is 30Ω.
The measurement is whether it is symmetrical thus carried out between the two outputs X3-X4 or asymmetric, an output to GND, the other output to the load.
calculation of the output resistance according 4:01
6:01 The slope s = Ie / Ie = UT
6VDC/2K2Ω = 2.7 mA emitter current
UT = 40mV voltage temperature silicon
s = 2.7 mA/40mV = 68mA / V
1 / s = 15Ω
6:02 ree = 2 / s = 30Ω

7:00 output resistance rkm to X3 when X4 is open and vice versa:
sine of 1kHz-20dBu input on feed. Load resistance Sun debug output on X3, that the level of breaks in half. It is an open X4. The value to be considered rkm is 560Ω. The same value results in the measurement of X4 with open X3.
calculation analogous to 4:05
Rages R1 = R2 = II 1K1Ω
Rkges R16 = R15 II II II R17 R18 = 1K1Ω
rkm = (Rages + 1 / s) II Rkges
rkm = (1K1Ω + 15Ω) II 1K1Ω
rkm = 554Ω

8:00 The following measurement shows that the output can float:
of 1KHz sine-6dBu (equivalent to 1 Vpp) to the output X3 celling. Inputs are shorted it. The signal which is fed to X3 comes in, X4 out. The same vice versa so signal on X4 from X3 comes out.

This is also true for applications with FET's and tubes. Especially when
push-pull driver with Tubes get the start in Blog declared properties that offer a significant technical advance over the 'prior art'.

To be continued ...

(23.08.2009) Reactions to this blog in forums, it may be laughed:

"The ELKO 'attempt to Forum discussion on the blog. Warning, this thread now consists of several Pages, which you can choose above right. Meanwhile, I have the impression that people are overburdened with the subject. Reason: differential amplifier on the search for a basic link to the topic, I came across this page (release 16.07.09) . There, they claimed, the difference amplifier is the basic circuit of the operational amplifier and the picture shows a push-pull amplifier. This then had to serve for the explanation of the differential amplifier. I tried something decent in the associated forum to address . Obviously not because you understand it, but my "world view not to get shaken", one has in the second Tests (call 22:07:09) nevertheless already struggled through the LTP. To my question whether the difference between difference and is known push-pull amplifier, was to me the answer. Consequently, is it possible not to provide push-pull CMRR for the amplifier. 5th Page in the thread logically only if the declaration on the common-mode rejection from the 3.Versuch (release 18.08.2009) reads. By the way: Since the push-pull amplifier differential and total gain (ideally) have the same amount, the ratio 'CMRR' is then equal to one. Whether this criticism, the artist encourages thinking from self-proclaimed "electronic compendium 'to order? After five pages (!) Debate and hostility in the forum, I have little hope.

* www. ebmule de. Herrlich, the reaction of the Ing ... the breaks on the Gleichtaktverkopplung understanding between the differential amplifier tube stages. http://www.ebmule.de/printthread.php?tid=1147
quote from 07/27/2009 20:43 :"... your insane Gleichtaktverkopplung between the tubes exists only in your head. is the purely technical connection between the tubes cold. They can be easily ground to alternating voltage, without even one iota of change in the function. ... " End of quote.
but he had, see Start Block bottom, the Anordnung für sich verbuchen wool. Der Thread steht in der Fassung vom 06.08.2009 as pdf copy zur Verfügung und kann auf Anfrage privat zugesandt were.

Letzte Bearbeitung am 03.September 2009 (Text ebmule hi-portal)

Der folgende blog deals Schutzmaßnahmen in der Endstufe.

This work is licensed under a Creative Commons
Attribution-Noncommercial-No Derivative Works 2.0 Germany License .

How To Buy Usa Outlets

Katodenfolgern difference amplifier for driving the push-pull stages.

Hello,
in this blog I want to show you a push pull driver stage. I build it in a 6 x EL34 Power Amplifier ( schematic ) and I am very satisfied with this kind of driver .
It consists of two differential amps. A conventional cathode coupled differential amplifier at the top and an anode coupled differential amplifier at the bottom. Both differential amplifiers are forming a kind of constant current draw to improve each other. There will be no change in charge of the coupling caps from the cathode coupled to the anode coupled differential amp. This prevents 'blocking' of the tubes and cross over distortions .
Experimental BJT bread board circuit

Differenzverstärkern muss oft ein Katodenfolger je Ausgang nachgeschaltet be in order to drive triode with sufficiently low impedance. With the help of 'Fourth Circuit Design' can be of two Katodenfolgern build a differential amplifier with anode coupling. Through a clever interconnection with the controlling differential amplifier in Katodenkopplung additional time constant grid current free limit is reached, there is no work-shift and Distortion come with that, not occur. The differential amplifier serve each other with a current source which improves the quality of the differential amplifier even further. The picture shows the interconnection of the two differential amplifiers.


The following are the various circuit components described and subsequently launched a example circuit for a power amplifier .

In a conventional differential amplifier with Katodenkopplung the output to the anodes of the tube is removed.

Katodengekoppelter differential amplifier
The cathode current is distributed, depending on the voltage difference between the bars on the anodes. When using a constant current source, as shown in the picture, there is complete common mode rejection. This means that even under asymmetric activation is obtained at the anode equal-phase signals. Condition for this is that the load is equal to the anodes. A current source requires at least one additional appropriately wired tube. A good compromise, come without this power source is charged with a DC resistance. This is called 'long tail' and the wired as a differential amplifier tube (or transistor) pair is therefore long tailed pair , briefly called LTP. The multiple stages connected in series provides a more common mode rejection. Another reason why you invest in the tubes rather than an additional LTP level in a power source.
is even more favorable to as in the circuit above, use the following differential amplifier as a power source for the previous difference amplifier. Serving as Katodenstromquelle triode control changes of the total current and get so effective against the desired current source behavior r> R by circuitry measures.

triode can be constructed with a differential amplifier in anode coupling.

anode coupled differential amplifier
case of symmetrical control is no signal voltage at the anodes. Any imbalance causes an anode voltage signal that controls the passage of the triode. When using a constant current source, as shown in the picture, there is complete common mode rejection. This means that even under asymmetric activation is obtained at the cathode equal-phase signals. Condition for this is that the load is equal to the cathode.
The output resistance between the cathode is, as between two different Katodenfolgern, 2 / s [s = slope]. They are measured in the sample circuit 570Ω. The anode-side 'long tail' at the anode-coupled differential amplifier is at the open circuit voltage gain μ 'worse' than the cathode-side 'long tail' at katodengekoppelten differential amplifier. Triode with a high penetration and low residual voltage enable a high-resistance anode resistance which improves common mode rejection. However
are triode with very high penetration as Katodenfolger not really suitable. How to find the best cathode follower. In the presented application, the anodes of the small signal Katodenfolger moderately differential amplifier with the grids of the Katodenfolger katodengekoppelten coupled as a grid-based amplifier. The above reduced action of the 'long tail', due to the μ anode coupled differential amplifier, is thus more than compensated. Through this Gleichtaktverkopplung both create differential amplifiers are mutually optimal operating conditions.

The following is an application example of this driver in a booster :
(Tubes along the signal path ECC82 → ECC88 → 6N6P → 6xEL34)

The control of output tubes to be avoided in the grid current range control. When controlling an electrically coupled Katodenfolger You hold the power grid by appropriate choice of anode voltage for the Katodenfolger of range. At the anode-coupled differential amplifier is determined by the resistance common anode or the anode power source the maximum grid current of the output tube. The grid current use at the Katodenfolger determines the grid current of the output tube. The well-known problem with the change in charge of the coupling capacitor and the associated operating point is thus moved from the output tube grid to the grid of the driving Katodenfolgers. This change in charge of the coupling capacitor prevents the circuit. The top differential amplifier detects the grid electricity used to power tubes as a change of the total current and limits the control of the Katodenfolger still energized grid area. This does not change the charge on the coupling capacitors. The operating point is stable. Now you can size the coupling capacitors generously without fear Nachkriechen the operating point must be. How

the circuit does that, you can Oscillograph to the grids of the output tubes. The oscillogram shows an overdriven 1KHz sine wave.


(The same oscilloscope also obtained from the secondary winding of a Zwischenübertragers, which receives its bias on balancing resistors, image .)
on the 0V line, here grid electricity use is flattened, the upper cap of the sinus. At the lower end is added for a bit. This happened here in the anode current-free area and therefore has no effect on the output, especially as the push-pull signal is unaffected. The output is as desired in overdrive top and at the bottom.


It's not the dreaded crossover distortion by shifting the operating point.

Appendix:
first calculating the internal resistance of the equivalent current source for the differential amplifier katodengekoppelten:
This is formed by the anode-coupled differential amplifier. The common cathode resistor is:
1:01 Rkges = R9j R9h II II II R15J R15h
= 1 / (2x (1/47KΩ 1/56KΩ +))
= 13KΩ. This is
μ-times multiplied to the anode side: 6N6P
μ = 22
1:02 μrkges = 22 x 13KΩ = 286KΩ
Since the voltage drop at the common anode resistance Rages of katodengekoppelten differential amplifier control the triode of the anode-coupled differential amplifier, this resistance Rages μ-times multiplied added to μRkges:
1:03 Rages = R9c II R9o NB The 1MW resistors are negligible.
= 1 / (+ 1/47KΩ 1/47KΩ)
= 23KΩ
1:04 μrages = 22 x = 506KΩ 23KΩ
added together
Both resistance values yield the internal resistance of the equivalent current source for the differential amplifier katodengekoppelten:
1:05 μ (Rkges Rages +) + = 286KΩ 506KΩ 792KΩ
r =
By 'long tail' on the other hand, only about
1:07 would Rlt = (50V + 135V) / 7 mA = 26KΩ achieved.
Duch, the combination of the two differential amplifier of the differential amplifier katodengekoppelte cheaper by a factor of 30 as a single with 'long tail resistance'.
is noteworthy that most of the equivalent current source resistance r = 792KΩ is formed here by the common-mode control via μrages = 506KΩ. This finding is very valuable and applicable to many of these differential amplifiers.

second determination the equivalent internal resistance of the power source for the anode-coupled differential amplifier:
recognize this, we must, that causes any change in current to the anodes in parallel a corresponding voltage drop at the common anode resistance Rages katodengekoppelten the differential amplifier. This controls the two triodes of the anode-coupled differential amplifier in common mode at the bars. This μ-fold more sensitive grid control circuitry replaces the power source to the common Triodenanoden. When anodal 'long tail' of the anode-coupled differential amplifier could be a 'long tail resistance' of maximum (360V - 50V) / 7mA allow = 44KΩ. The the 'long tail' corresponding equivalent current source internal resistance, which is formed by the grid control is, in contrast μrages = 506KΩ. By combining the two differential amplifiers of the anode coupled differential amplifier cheaper by a factor of 12 as a single with 'long tail resistance'.

third common mode rejection and CMRR:
Through the interconnection of the coupled differential amplifier of the differential amplifier katodengekoppelte Katodenfolger as common mode signals on the anodes of the anode-coupled differential amplifier. These are coupled according to the penetration of the cathode. The grid control on the katodengekoppelten Differential amplifier counteracts this. Therefore favors a smaller penetration and a large common-mode rejection Rages.

CMRR is 60 dB measured in the application example.

calculate CMRR:
To calculate first the common-mode gain vugl
3:01 vugl 1/μ-Rages/μ = (+ Rages Rkges)
condition: Rkges>> 1 / s, for μ the value of the anode-coupled differential amplifier.

with the values from the example circuit:
vugl = 1 / 22 - 23KΩ/22 (23KΩ 13KΩ +)
vugl = 0.045-0.029
vugl = 0.016 corresponds to-36dB

The push-pull amplification for the differential amplifier is calculated katodengekoppelten
3:03 vuggkd sx = (μ / s II Ra)
where for μ s and the values for the triode in katodengekoppelten have used differential amplifier. These are determined from the charts to the tube.
vuggkd = 5mA / V x (29 / 5mA / V II 47KΩ)
vuggkd = 5mA / V x 5163Ω
vuggkd = 26 times

The push-pull amplification for the anode-coupled differential amplifier is calculated as:
3:04 vuggad = (1 - 1 / μ) x (Rk (Rk + 1 / s))
vuggad = (1 - 1 / 22) x (26KΩ (26KΩ + 285Ω)) = 0.95 x 0.99
vuggad = 0.94

is the push-pull amplification of the circuit:
3:05 vugg = vuggad vuggkd
vugg x = 26 x 0.94 = 24 = 28dB
vugg

3:06 CMRR is:
CMRR = vugg / vugl
CMRR = 24 / 0.016 = 1500
CMRR = 28dB 36dB + 64dB =

With Long Tailed Pair and Katodenfolger contrast, only one would
3:07 Rlt / Rages = 26KΩ / 23KΩ
(see 1:07 and 1.03)
= 1.13 or 1.1 dB CMRR
= 1.1 dB + 27dB = 28dB reach.

CMRR is improved by the Gleichtaktverkopplung of Katodenfolger and Long Tailed Pair presented here provide the Anodnung in this circuit to the 63 - fold or 36dB.

4th output resistance:
rkk The output resistance between the cathodes is expected to be 2 / s because the internal resistance of both cathodes are comparatively small signal in series. From the measured value for RCC can calculate the slope s:
4:01 s = 2 / rkk
s = 2 / 570Ω = 3.51 mA / V
1 / s = 285Ω
The reciprocal of the slope is s multiplied by μ Riak the internal resistance of the triode.
4:02 Riak = μ 1/sx
Riak = x 22 = 285Ω 6270Ω
this value may be to control in Ia = f (Ua) chart to the nearest operating characteristics set as tangents.

A simplified formula for calculating the output resistance between cathode and ground brings rkm an extreme value analysis:
4:03 For Rages = 0:
rkm ≈ 1 / s
4:04 For Rages = ∞:
rkm ≈ Rkges

It follows:
4:05 rkm = (Rages + 1 / s) II Rkges

With the values of the circuit:
rkm = 23KΩ 13KΩ II = 8K3Ω

The measurement showed scarce 8KΩ. It is also interesting that the output actually behaves like the equivalent circuit in subscribed Anordunug with transformer. If an output short-circuited small signal moderate, the output voltage remains unchanged as desired. This means the amplitude doubled on the opposite side, then.

The Scoop: In
has a forum in the scene of well-known user in my opinion just trying to notch up this development. http://ebmule.de/showthread.php?tid=1147&page=10
quote from 'User' from post # 246:
"... To prevent further discussions from the outset: that which Darius here trying to sell as an innovation, I have the end of last Year, already presented in a completed device in a similar configuration. ... "End quote http://www.roehrentechnik.de/forum/gdgt-300B.png
In the picture,

he has added to the review, it shows the old arrangement known differential amplifier controls Katodenfolger. Of course, all beautifully colored, fitted with simulations and positions the tubes as in the circuit here in the blog. Did he really believe to get through it?
As the saying goes, if I do not get it that no one should have tried it in my opinion by all the advantages of one of the arrangement to ignore or talk away. While one tries to distract from the subject highlighting the advantages not to have to admit, the other looks for the current source and the target past the next simulated reality. Flaming worst form, as well as my real name, provided in an offensive context, have become one of them. Of course, all attempts to dissuade the user, this blog here to read! The
Thread is in the version 13.06.09. Pdf copy is available and can be sent privately by email on request. The following blog is

then this example circuit with transistors by measured.

last updated on 20/08/2009

This work is licensed under a
Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 Germany License .