Open Letters #03 05 мая 2000

Nemo open letters № 3.6

445027 25.05.2000


    Hello, dear (c) Nemo!


   1. I received your letter dated 20/04/2000.

   2. Judging by the description BP9022 - a self-excited 
blocking oscillator (as well as else?), similar to television 
MP-3 (Journal of the radio amateurs "№ 1 for 1997 I

never found).

   And MP-3, in my opinion, there are two drawbacks: 1) often 
leave their damaged electrolytic capacitors in the feedback 
loop Communication (14C in MP-3-3). Perhaps the reason

This is a pulse mode, and
can me such a source of random row
suck, 2) measuring the voltage
not removed from the power outlet (such as the power supply IBM 
PC, via the opto-coupler), and additional. A this is, after 
all, reduces the stability of the output voltage (5 V). 

   The most suitable power supply for
Spectrum'a, in my opinion, is as follows:

   1). The integrated PWM controller type
TL494 (our analog 1114EU4 worth a total of 12
p. when sold at retail) - good "run-in PSU IBM PC, and can work
in one-and two-stroke mode

   2). The power stage can be anything -
push-pull, flyback, just screwed, although preferable flyback
because of the natural defense power transistor. The switching 
frequency should be designed for domestic use

transistors, the same KT872A.

   3). Voltage on power "+5 V" output from the opto-coupler; 
+12 - after KR142EN8B (7812-CPU) - or vice versa EN8B analog 
7812. 

   4). To protect the hard drive, sensitive to rejection power 
can be should organize a separate regulator

on the +5 V linear type, for example,
KR142EN5A. This will limit the current consumption
and possibly improve the transient response. Zasinhronizirovat 
work of all the channels no problem. The cost of BP course 
increase, but better than 1 time to pay for BP than 5 times the 
hard drive. By the way, thank you for warning about the danger 
of burn Winchester. Efficiency, of course, will decrease, but 
with This can also be reconciled.


   5). Desirable channels at -12
V and -5 V with stabilizers, respectively, 7912 and 7905. The 
presence of these channels encourages the purchase of 
HAYESmodemov, but with On the other hand for the installation 
HAYES'a usually buy PSU IBM PC, and not another.


   Produce such a PSU you can try
and handicraft, but the prefabrication
preferable.


   3. You write that between MS146818 and
512VI1 likely to have differences, which
unimportant. I can say the following:
IC KS82C6818, which was bought as an analog MS146818, work did 
not, although earned a master oscillator, and 512VI1 worked 
under the program in the same scheme.


   Download counterfeit software with technical. Doc. I'm not 
on MS146818 going to, had no idea what

possible. Tech. Doc. MS146818 on me yet
is not needed.


   If you came to my translation of 54 p.
for technical. Doc. at MS146818, then send
instead

   ZX-Format № 8.

   Op. let., which I have, amended on 2/24/2000, so if the 
latter edition has a significant (at your

view) update, send it. If
not, then something from the archive.


   P.S. Will ZX-Format № 9?



                               05.05.2000


              Dear N!


   2. First, some general comments
character.

   2.1. Discuss power supply circuitry
in "Op. let." hardly appropriate. Especially in
such an extent. Hardly anyone would be interested. Well, 
consult a private not see the point. This is already

other prices. For information: h tutor
in SP-B costs around $ 2 -5 per hour.

   2.2. You seem essential means
not the issues that really matter.
Circuitry of course important, but as an abstract 
self-contained theme it is vacuous, ie, makes no sense. Variety 
demomeykerstva. 

   2.3. Operational and производственнотехнологические 
approaches to addressing PD vary widely. Therefore, I always

amuse users talk about
production - it is very difficult to explain that their 
arguments are inadequate. I think when reading further you will 
have the feeling that it's just the birds are singing. 

   Hereinafter, purely concisely:

   - "Self-excited blocking oscillator - how else?" This 
terminological subtlety, though perhaps "self-excited" - not 
quite specific. Just is, for example, waiting blokinggeneratory,

and they too can do PD.

   -"... Fail electrolytic capacitors ... " This is a common 
problem for all BP, including the RS-shnyh. Electrolytic 
capacitors - is generally the most unreliable elements. With 
regard to C14, then under the scheme, he is working at the 
reactive power. And the nominal value typically 63 V, although 
actually the capacitor DC voltage of several volts. Too "smart" 
technologies (In some plants), put back

35 V or even 16 V. This works for the time being,
to time. In addition, the capacitors
C50-35 and there are Armenian "spill." This
altogether separate issue.

   -"... Measuring voltage ... " in
BP9022 is removed from the output of +5 V, - so he
and differs from the MP-3, and further, through the comparator 
/ reference voltage KREN1 through optocoupler operates moment

switching thyristor VS1 KU112A. As for the MP-3, it is the 
stabilizer of the magnetic flux in the core, and has already so 
far - because the actual voltage stabilizer. To this 
circumstance is not so much influenced stabilizing properties 
of the scheme for voltage, it employs a special partitioned 
"layout" of the windings in the window. Instability of the 
output voltage -1% BUT IT IS GUARANTEED ONLY TO EXIT

135 V, - on the other stresses we are not
goes. Because in the TV small multiplicity
load current (as opposed to computer) -
this is permissible.

   -"... Integrated PWM controller type
TL494 ...- respectively. The power supply the most 
sophisticated sites are responsible motochnye [???] products. 
They are, incidentally, is the most expensive. A question cool 
the chip should be discussed in networks - there is the 
contingent and appropriate level. Notify you by

confidence that power high-frequency
transformer in the party from the hundreds of pieces will cost 
about the same number as Used PSU from PC-ka in working 
condition, bought kakomnibud cellar. In fact, the cost of the 
PC-power supply in the production of is about 5 - 10% of the 
price of computer (ie, approximately 100 - $ 200).

Everything that you see MS-Shnogh - it is garbage to the 
European / American garbage dumps. And to make any conclusions 
on cost production based on these post-industrial landscape, at 
least stupid. This creates certain problems,

as there is such a thing as price expectations. This is when 
the sheep begin to judge production cost. To do something 
impossible. I will not hide we also have a high-tech. In

Sobchak's reign (he was a governor in the SP-B to Yakovlev) was 
constructed Only two high-tech factory with the active

support of the international community. Both plants
- Garbage. When something
leaves, for example, Western
garbage dumps of electronics, the authorities pay more 
"traders" for garbage. Then same goes for illiquid - "morally

obsolete "models. It is clear, where are the prices?

   -"... Well run-in PSU IBM PC ... " On
really good run-in process vparivaniya debris population. As for
technology, production, she obkatat
THERE, not here. And the technology - it is know
how, praxis - it is not removed from the debris.

   -"... Because of the natural defense power transistor ... " 
(It should be stipulated that the entire letter deserves a 
detailed comments, ie, should not think that

the rest corresponds to something, somehow
meanings. It's just a frame [???]. For lack of time and place 
chosen by the most fat "pearl"). Flyback circuitry sources 
prevailed recent years on the grounds that they

the most simple. Meanwhile transistors
work for, in worse conditions than
in other types of circuits. The utilization ratio of 
transistors in the current, for example, worse than a 4 times 
higher than in the corresponding push-pull configuration. 
Moreover, the current maximum achieved in the most adverse

time - namely at the time of shutdown.
Therefore, the transistors must be used on the verge of 
admissible modes and VERY POWERFUL (compared with the power of 
the source). The working point of the transistor

"Flies" in the most dangerous area, and
it is in the upper right corner of the CMR (secret acronym - 
the region of maximal regimes). With regard to short-circuit 
load, so, in the flyback

sources, it is less dangerous. But it is in
flyback sources, there is another problem associated with very 
poor using the transistor current - and

Namely, an underestimated the input voltage. In
TV source MPD IS SPECIAL CASCADE,
disconnect the power at an undervalued input voltage. And the 
situation between it is likely - for example, poor contact in 
the socket, or breakage of the connecting cord with a "cold" 
ohmic contact. 

   -"... Switching frequency ... " not so
obviously related to the type of transistor. AND
in general, the initial assumptions for the design PD are 
required power (which, incidentally, is limited by the type and 
size of the body - that is, BS in design, as well as fee, 
"under the body." In "Korvetovskom" housing, for example, the 
maximum power PSU - 100 W or less, or body of the melt). 
Frequency - this is a compromise to be achieved in a number of 
contradictory requirements. Usually chosen frequency

just above 20 kHz to avoid acoustic noise.

   -"...+ 12 V - via KR142EN8B ... " - So
done in BP9022. By the way, not the best solution in the sense 
that the maximum current - 2A. Include parallel rolls can not be

a pass transistor reduces efficiency, and current protection - 
only from flyback circuit and its properties. Ie if you need 
more 2A - continuous problems with the rolls. 

   -"... KR142EN5A to the hard drive. " Wonderful ...

   -"... 7912, 7905 by HAYES modem. Try, at least mentally put 
it all in one pile, and evaluate the resulting shed. It is also 
useful to remember that each ROLL - is a separate winding 
transformer with an appropriate contribution to the price tag. 
Not to get a stove. 

   -"... Stimulates purchase HAYES-modems ... " And it needs to 
be stimulated? Understand modems are all different - solid, 
liquid and gas - even if imported.

Support and promote such a motley hodgepodge IMPOSSIBLE. And who
will be repaired? Who will give a guarantee? This, of course, 
great that it costs 200 rubles. But How much is the connection? 
At least 300 p. because required kulibinstvo particularly

perverted form. Probably, for 300 rubles.
no one will undertake. Therefore, "podpihivat"
users to PC-shnomu garbage tank
it hardly makes sense. HAYES needed
only in one place - namely the Gateway -
Hub to enter the transport
Level I-net. Ie at BBS, - yes, and
then, only one of the city. Much
easier to organize (or rather, less difficult)
production HORIZONTAL modems under the standard joint (bus or, 
better yet, Centronics) and ALL HURT their support / promote. 
It is curious that Kondratiev thinks, for example, on the 
contrary. But that is because that he never dealt with it 
professionally, ie, for the money - regularly and respectively. 
If he tried this foolishness instantly to erode from his

head. Ie This can be done and the level of
kulibinstva, but can not be done -
ie create a network HAYES'ah.

   -"... Can try and homemade ... "
Price of power obtained at least 500
p.

   -"... Prefabrication ... " - Unrealistic, too small amounts, 
too low price expectations, too little custom content 
Spectrum'a. As for the existing power supply - it is 
unmarketable products ... Because the price was. 


   3. "KS82C6818A". No doubt
that we can invent such a scheme in which analogs will not 
work. Moreover, we can devise a scheme where half similar 
crystals will refuse to work. Catching these glitches may even 
completely take possession of man. The technology exists such a 
thing as reproducibility. Good design (note, NOT

LAYOUT! - Because the concept of development is
and technology implementation) works on any garbage.


   4. ZX-F № 8 sending, about the ZX-F № 9
uncertainty.


   5. Sending the first issues of "Op. Let", and
is number 1 and number 2. May find something
interesting.

                                (C) Nemo.

P.S. Likely to read such responses are not
very nice, but I see no other way to "filter" in "Op. let." 
frame. Idle Manilov argument best left to themselves, or 
discuss it in networks. However, if the question was

and in the case, it is always ready to explain the most 
detailed manner. 

   When they say "well run-in production" means the technology, 
and circuitry, so the last thing. Take, for example, the same 
MPD. There Some molds and dies are millions

Rubles. But due to the volume, as befits a high-tech, the price 
of parts - a cheap. That is why the production of television 
sets in the USSR was the most Tech, - ie this is

HIGH TECHNOLOGY. But not any there megahertz and megabytes - 
this is the Corollary. Building "Corvette" MORE high-tech than 
the RS-shnye Corps. It is clear that it is not obvious, 
especially if the TV and see a lot read a lot of PC-shnyh 
magazines. 

617170 24.04.2000


           Hello, Nemo!


   First I want to thank you for
performance (or rather, a re-execution) of my previous order. 
With this drive all the disks that I have,

are working normally. Apparently, as you pointed out in his 
response to my questions, there is some incompatibility with 
720 Kb drives and floppy disks - not all of them work. Also, a 
diskette with the ZX-Format № 8 was normal. I sincerely thank

You for this additional work.

   Now my new order:

   1.Diskety "Isot" 5.25 ", DS / DD - 20
cu

   2.Spravochnik "Digital devices."
Textbook for higher technical schools. Pukhal'skii
GI, Novoseltseva TY

   Total to pay 20 +45 = 65 * 3.4 = 221 rubles.

   I sent money by postal order
Today, April 24.

   Also sending you stamps for 15 rubles. -
As I understood from your price list, so
required to obtain an order from a floppy disk
"Open letters".

                    C Yours sincerely, N.

P.S. Totally forgot to ask you about the service: in his time 
(08/23/1999) I spoke with order catalog "LOGROS" a to Akimov

Michael Anatol'evichu. Then again wrote
it (somewhere in December 1999) with a reminder about the 
order. But so far not received neither ordered nor simple 
answer. Could you somehow connect with Akimov and find out how 
things are going with my order (or am I wrong to do anything). 
I would be very grateful if you would help me with this.


                            06.05.2000

              Dear N!


   Of your claims to Logros'u not clear
Do you pay the money or not.

   Logros no longer works for Spectrum'u.

   If money were not paid, then just need to take note of that
Logros no longer works.

   If you pay, you must provide:

   - Date of sending money

   - The amount

   - A list of the order.

   Firm (s) Nemo is not liable for the obligations of Logros'a, 
and yet However, if you can do something,

it will be done.

                                (C) Nemo.