Jo Tech Service   Joar Falstad

  
 INDEX



 
A new idea  in audio  noise reduction .
Strong   pass audio filter, with adjustable setting of minimum pass level.
 

Bad input  gives bad output ,  but there are exeptions when the output result depends on human hearing.
Our ears are not sensitive at all to volume change.  3dB is the absolute minimum audio volume difference we can hear.
+3dB  equals to Signal voltage x 2  , using a linear scale.

By using our strong pass audio filter to eliminate background noise, all signals smaller than the minimun pass level are reduced by a  factor, typical  20dB .
You don't need a dB-meter to make shure the filter is working. This noise cancelling function is strong,  something you can really hear.

Idea & solution by
Joar Falstad.   
Jo Tech Service 




No signal delay.  No change in pitch, maximum volume or tone balance .

Measured  audio
volume reduction outside pass level:   up to  100 x  or   20db
Adjustable
audio volume reduction outside pass level to come.
 
Strong pass audio filter test  :

Demo video , youtube



Live   audio background noise reduction or removal , hiss cleaner , minimum signal filter .
Prototype.  
Test version.




Read more   /   some video examples :
Real time analog audio   noise and hiss cleaner ,


Later  Mono test version 

Line   signals  in consumer equipment has a standard max value :  0.316  Vrms 
Tape , Tuner and Aux signals are normally close to the standard of line signals 
 

Our strong pass audio filter  has a 
in / ouput limit of  : 4Vrms 
All versions have  galvanic insulated transformer output.

A similar stereo ( possible commersial ) version  is in the making.  

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Service  &  Repairs

 





A Pilot 240B for test and repair,   just something to memorize.
This unik valve stereo amplifier is now back in action, after a long rest. 
One of the best amplifiers  in any class. 

 


The Beard   P35
and 
most other  VALVE audio   amplifiers   have Direct Coupled audio signal inputs.

Note!      DC
audio signal inputs are not compatible with audio signal outputs found on modern preamplifiers or pc earphone output . 
 A DCvoltage pulse of several volts from a pc or modern preamplifier at Power ON, to this type of signal input can overload and damage the valve in the input stage

Convert to AC audio signal inputs .  Capacitors  is  a hint.

Note!  High Voltage inside the amplifier

S
elf oscillations in the amplifier.

Some input stage valves, mainly triodes, have internal positive feedback , this can be locally neutralized.
You'll get the best overall result by doing just that, before adding other oscillation cancelling parts in the input or feedback circuit.

Natural, non colored, high quality sound.
Even to day,  a good quality VALVE amplifier  has the best soun
d . 
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High end 
amplifier  update
Sony  TA - 5650  Vfet pre & power amp

drifting bias fix.

Sony
S2
Mosfet pre & power amp
 Great sound quality .  
 Hot inside, possible to fix.

Sony TA - 1120A
Solid state
pre & power amp 
 Great sound quality .


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We are all most creative when we are "forced"  to find a solution .
  

Some older  ideas and solutions
, composed at our workshop.



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Industrial Hardware.

PLC
-  analog multiplexer
Idea & solution by Joar Falstad


Industrial Analog Multiplexer
Detailled schematic examples
0 - 10V  /  4 - 20mA



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Windows Program  +  industrial standard digital i/o hardware
 

Idea, design and programming by Joar Falstad



Advanced Public Address System   

Speakers  are included and arranged as group names. Latest USB-version has a capacity of more than 32000 patterns.

Manually speak to the addressed group.
Manually
play a prerecorded message, to the addressed group of speakers.     USB ver.
21 timecontrolled   fixed  announcements, will automatically Play a prerecorded message, to the addressed group of speakers.
Timecontrolled announcements,   w/separately file controlled speaker group addressing .
Sensor control will activate, log and play a prerecorded alarm message, to the addressed speaker groups.


Later version , USB



PC controlled. 
Detailled schematic examples.
ISA demo version download
First ver : ISA  Win95.  
Latest ver :  usb Win7
XP
PC interface: Advantec USB 48ch DIO
Inputs and Outputs: Advantech PCLD-8761   24 ch. input / 24 ch. output .   Tested ok.

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Windows Program   +  industrial standard  analog i / o hardware

Idea, design and programming by Joar Falstad


AD/DA Conversion and Data Acquisition made easy.
Easy setup. Easy to run and control.




Time and Masterfile controlled AD-DA conversion ,
Easy setup. Easy to run and control.
The Masterfile
is generated by the program itself , as a linear "Unit Value" function from a Time ref to the next "Unit Value" at the next Time ref.
There is no limit in number of Time ref's  from tne project start time to the final stop time.
PC clock is used to control the Time

First ver : ISA , Win95 .  Early demo version download
Next ver : PCI , Win98 . Plug & Play.
We are now working on a USB ver in Win7




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Win 7  Program.     USB - DMX hardware
 

DMX  stage  lights control .

For your own and PC safety:   Use an insulated DMX USB interface . 

Program has separate  control of all spots .
Not designed for disco.



Stage & other  . 
How to connect  & more 

 
Free link to:  
Enttec  compatible  DMX    open source VB6  program download .  1ch. to 512 ch.
  Tested OK with :  Win XP + VB6 runtime files + VB6 installed on your computer

Free download:    DMX program
. Compatible with most DMX controllers.
Tested OK with :  Win XP  + downloadable   VB6 runtime files installed on your computer.

Enttec or compatible,  like Splabs DMX.
Insulated USB - DMX controller.    1 - 512 ch. 
Insulation USB to DMX output line connection  1.5KV
Internal 512 cannels memory w/repeat.
Works with most DMX programs.
Ask us

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History. 
Ships alarm schematics and more


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Vingtor, Stentofon

Old / obsolete intercom systems.  Replacements. Repairs.

Compact 32-2  /  VMP32-2
Old / obsolete intercom systems.  Replacements. Repairs
This system is still used on ships.

NOTE! 
Power OFF when plugging / unplugging any board.
If done with power ON, most IC's  on the actual board
will blow
Some IC's are hard to find. 

Fixed repair prices , exclusive MVA / VAT   2017 / 2018 :


Examination of all boards in the VMP-32 exchange + message / mail to the customer  NOK1500.-

CPB / CPB-2 repair  NOK6500.-
SLB / SCB / PRB / RPB repair /  Each board   NOK3500.-
 
mark all SLB boards with a position number.

Station indoor, desk or wall, w/handset  :   VMP 619
Cable from station VMP 619 to old modular 4pole  wall socket , found on ships:  NOK150.-
 
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Zenitel, AlphaCom,  ACM  
 


GREEN LED = OK
Later systems, often used on ships.  
Replacements. Repairs.
Manufactured also today . 
Compatible with Vingtor & Stentofon  wireing and stations.

NOTE! 
Power OFF when plugging / unplugging any board inside the exchange.   
If done with power ON:   the actual board is damaged beyond any repair + possible damage to other boards!


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Monacor Catalog  
We are one of several Monacor suppliers in Norway.

100Volt line. Pa speakers & amplifiers .
Monacor stage audio and DMX light equipment
Alarm systems ,  video , backup  , ip adressing, wireless and more.

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Domain:       Jotech.no     ( registered on 20-03-2001
)

contact:       Joar Falstad

phone:          +47  99718408

Mail:            mail@jotech.no
  &                 falstad.joar@gmail.com

url:                http://www.jotech.no

Company:     Jo Tech Service  Joar Falstad, Lykkmarka 53, 7081 Sjetnmarka, NORWAY



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A big  car company has now taken the  same domain name  . " jotech "
To protect our site  and  keep it seen on the internet , we'll  continue to add nice pictures , mostly from Norway.



 Norway , Trondheim


Morning view from the car, at E6 in Rotsund .
Norway, Lyngen alps  , Havnnes ,   Rotsund ,  Nordreisa



Norway, Ekne Falstadberget
Nostalgy from the 70's.  With Vital 15 feet




South Africa .  Cape Town


South Africa .  Cape Town

South Africa .  Cape Town

South Africa .  Cape Town

South Africa .  Cape Town

Norway , Malvik, the ghost tree

History from mid 90's . 
Windows95 , ISA controllers, homemade hardware , this project was initially made in Visual Basic 3 .