From twibright at hispeed.ch  Tue Feb  3 11:18:02 2009
From: twibright at hispeed.ch (Karel Kulhavy)
Date: Tue, 3 Feb 2009 12:18:02 +0100
Subject: [Ronja] Progress report
Message-ID: <15384020.1233659883141.JavaMail.root@viefep15>

Hello

I have made a 50V power supply for the photodiode. First I looked at some chips but they were difficult to get. Then I tried a rail to rail opamp and a diode-capacitor cascade. The available one for me was ICL7621 which turned out to betoo weak and too
slow.

Finally I took a 74HCT14 oscillator and 6 transistors to make a two-phase push-pull
emitter follower. That works just fine. Produces regulated voltage across a 47V zener diode.

The cascade is different from Greinacher/Cockroft-Walton the capacitors are not
connected in series but in parallel.

Karel


From twibright at hispeed.ch  Tue Feb  3 11:59:44 2009
From: twibright at hispeed.ch (Karel Kulhavy)
Date: Tue, 3 Feb 2009 12:59:44 +0100
Subject: [Ronja] Progress report
Message-ID: <12339196.1233662384440.JavaMail.root@viefep15>

Hello

I have made a 50V power supply for the photodiode. First I looked at some chips but they were difficult to get. Then I tried a rail to rail opamp and a diode-capacitor cascade. The available one for me was ICL7621 which turned out to betoo weak and too
slow.

Finally I took a 74HCT14 oscillator and 6 transistors to make a two-phase push-pull
emitter follower. That works just fine. Produces regulated voltage across a 47V zener diode.

The cascade is different from Greinacher/Cockroft-Walton the capacitors are not
connected in series but in parallel.

Karel


From discover at fly.srk.fer.hr  Tue Feb  3 20:22:35 2009
From: discover at fly.srk.fer.hr (Silvije)
Date: Tue, 3 Feb 2009 21:22:35 +0100 (CET)
Subject: [Ronja] Progress report
In-Reply-To: <12339196.1233662384440.JavaMail.root@viefep15>
References: <12339196.1233662384440.JavaMail.root@viefep15>
Message-ID: <Pine.LNX.4.64.0902032114470.29143@fly.srk.fer.hr>


That sounds great!
Very digital :)

if I just may point out that "analog" solution could be as simple as
http://repairfaq.cis.upenn.edu/sam/teeny.gif

so if you have 12V supply, I believe you could easily use 2n3904 and
would not need more than lets say 4,6 turns in primary and about 24-30 
turns in secondary of one little transformer... check the part count :)
just one transistor :)

btw. for making such little transformers I use to "modify" inductors 
"transformer like" from PCBs of burned ccflamps, there you can also 
find some realy fine high voltage capacitors (400V) and other stuff, if it 
is problem for someone to get them :)

and if you like this analog solution to be more "stable" you could use 2
transistor schematic... widely available...

regards


On Tue, 3 Feb 2009, Karel Kulhavy wrote:

> Hello
>
> I have made a 50V power supply for the photodiode. First I looked at some chips but they were difficult to get. Then I tried a rail to rail opamp and a diode-capacitor cascade. The available one for me was ICL7621 which turned out to betoo weak and too
> slow.
>
> Finally I took a 74HCT14 oscillator and 6 transistors to make a two-phase push-pull
> emitter follower. That works just fine. Produces regulated voltage across a 47V zener diode.
>
> The cascade is different from Greinacher/Cockroft-Walton the capacitors are not
> connected in series but in parallel.
>
> Karel
>
> _______________________________________________
> Ronja mailing list
> Ronja at lists.pointless.net
> http://pointless.net/mailman/listinfo/ronja
>


From twibright at hispeed.ch  Tue Feb  3 22:01:40 2009
From: twibright at hispeed.ch (Karel Kulhavy)
Date: Tue, 3 Feb 2009 23:01:40 +0100
Subject: [Ronja] Progress report
Message-ID: <14209626.1233698501846.JavaMail.root@viefep18>

---- Silvije <discover at fly.srk.fer.hr> schrieb:
> 
> That sounds great!
> Very digital :)
> 
> if I just may point out that "analog" solution could be as simple as
> http://repairfaq.cis.upenn.edu/sam/teeny.gif
> 
> so if you have 12V supply, I believe you could easily use 2n3904 and
> would not need more than lets say 4,6 turns in primary and about 24-30 
> turns in secondary of one little transformer... check the part count :)
> just one transistor :)
> 
> btw. for making such little transformers I use to "modify" inductors 
> "transformer like" from PCBs of burned ccflamps, there you can also 
> find some realy fine high voltage capacitors (400V) and other stuff, if it 
> is problem for someone to get them :)

Do you know a source of new (not removed from broken electronics) standardized transformer cores that are easily available everywhere?

Karel




From discover at fly.srk.fer.hr  Tue Feb  3 22:39:57 2009
From: discover at fly.srk.fer.hr (Silvije)
Date: Tue, 3 Feb 2009 23:39:57 +0100 (CET)
Subject: [Ronja] Progress report
In-Reply-To: <14209626.1233698501846.JavaMail.root@viefep18>
References: <14209626.1233698501846.JavaMail.root@viefep18>
Message-ID: <Pine.LNX.4.64.0902032336350.773@fly.srk.fer.hr>


although I havent been buying such things, as I always find something
usefull in my electronic junk box :) this may be it

http://export.farnell.com/jsp/search/browse.jsp?N=500006+1000242&Ntk=gensearch_001&Ntt=transformer+core&Ntx=

from the main page at http://www.farnell.com/ it seems it should be easily 
available in large region

there are probably lot more electronic components distributors, like RS 
and others but this is first I could think of..

regards


On Tue, 3 Feb 2009, Karel Kulhavy wrote:

> ---- Silvije <discover at fly.srk.fer.hr> schrieb:
>>
>> That sounds great!
>> Very digital :)
>>
>> if I just may point out that "analog" solution could be as simple as
>> http://repairfaq.cis.upenn.edu/sam/teeny.gif
>>
>> so if you have 12V supply, I believe you could easily use 2n3904 and
>> would not need more than lets say 4,6 turns in primary and about 24-30
>> turns in secondary of one little transformer... check the part count :)
>> just one transistor :)
>>
>> btw. for making such little transformers I use to "modify" inductors
>> "transformer like" from PCBs of burned ccflamps, there you can also
>> find some realy fine high voltage capacitors (400V) and other stuff, if it
>> is problem for someone to get them :)
>
> Do you know a source of new (not removed from broken electronics) standardized transformer cores that are easily available everywhere?
>
> Karel
>


From gullik.webjorn at corevalue.se  Wed Feb  4 07:16:28 2009
From: gullik.webjorn at corevalue.se (Gullik =?ISO-8859-1?Q?Webj=F6rn?=)
Date: Wed, 04 Feb 2009 08:16:28 +0100
Subject: [Ronja] Progress report
In-Reply-To: <Pine.LNX.4.64.0902032336350.773@fly.srk.fer.hr>
References: <14209626.1233698501846.JavaMail.root@viefep18>
	<Pine.LNX.4.64.0902032336350.773@fly.srk.fer.hr>
Message-ID: <1233731788.17779.3.camel@core-laptop>

Why not use one of the "simple switchers" type voltage
regulators? Those are commonly available, need only a 
single inductor, and a shottky diode , have only 5 leads
or so, so they should be easily useable with airwire.

Max vout 60V or so, takes only a few mA, (if Iout is low)

Just a thought...

Gullik



From twibright at hispeed.ch  Mon Feb  9 08:44:53 2009
From: twibright at hispeed.ch (Karel Kulhavy)
Date: Mon, 9 Feb 2009 9:44:53 +0100
Subject: [Ronja] Transreactance amplifier
Message-ID: <5730905.1234169094102.JavaMail.root@viefep18>

Hello

I have invented (not sure if I am the first) a photodiode preamplifier that has theoretically better noise than the usual transimpedance amplifier found in commercial FSO.

The transimpedance amplifier is an opamp which has a
resistor between the output and input - like 100kOhm - the transimpedance. The noise of
a transimpedance amplifier is dominated by this resistor. The resistor cannot be increased because the amplifier output would saturate on a sunny day.

I split the amplifier into two stages. The first one uses a capacitor for transimpedance, the other inductor. Neither of them produce any noise. Capacitor reactance is 1/wC, inductor wL. When multiplied, you end up with L/C - a frequency independent response.

I have quickly tested a transreactance frontend and it seems to work fine. It produces a nice signal without distortion.

I have C=5.86pF, L=2.63uH and intermediate gain 25mS. That gives transimpedance of
12.3 kOhm.

Karel


From twibright at hispeed.ch  Mon Feb  9 21:38:02 2009
From: twibright at hispeed.ch (Karel Kulhavy)
Date: Mon, 9 Feb 2009 22:38:02 +0100
Subject: [Ronja] Transreactance amplifier schematic
Message-ID: <21479215.1234215482518.JavaMail.root@viefep12>

Here is an (unfinished) schematic:

http://ronja.twibright.com/schematics/mundaka.png

Karel


From discover at fly.srk.fer.hr  Tue Feb 24 22:29:24 2009
From: discover at fly.srk.fer.hr (Silvije)
Date: Tue, 24 Feb 2009 23:29:24 +0100 (CET)
Subject: [Ronja] Progress report
In-Reply-To: <Pine.LNX.4.64.0902032336350.773@fly.srk.fer.hr>
References: <14209626.1233698501846.JavaMail.root@viefep18>
	<Pine.LNX.4.64.0902032336350.773@fly.srk.fer.hr>
Message-ID: <Pine.LNX.4.64.0902242322410.17830@fly.srk.fer.hr>



Hi Clock,

please look at this 
http://www.techlib.com/area_50/enricosprojects.htm#Worlds%20Smallest

and

http://www.techlib.com/science/ion.html

you are designing a new rx module with prebiased pin diode, all enclosed
in metal box... what you may be getting from it is something similar to an
ionization chamber

therefore you might be picking some noise, if not from something 
radiactive in close to rx module, than from cosmic radiation maybe?

Anyway I can confirm that simple darlington transistor as used in
http://www.techlib.com/science/ion.html#Experimenters%20Chamber
can sense radioactive source.

regards,
s.


From twibright at hispeed.ch  Thu Feb 26 11:53:00 2009
From: twibright at hispeed.ch (Karel Kulhavy)
Date: Thu, 26 Feb 2009 12:53:00 +0100
Subject: [Ronja] Progress report
Message-ID: <17406143.1235649182274.JavaMail.root@viefep13>

---- Silvije <discover at fly.srk.fer.hr> schrieb:
> 
> 
> Hi Clock,
> 
> please look at this 
> http://www.techlib.com/area_50/enricosprojects.htm#Worlds%20Smallest
> 
> and
> 
> http://www.techlib.com/science/ion.html
> 
> you are designing a new rx module with prebiased pin diode, all enclosed
> in metal box... what you may be getting from it is something similar to an
> ionization chamber

The old RX is also a prebiased pin diode in an enclosed metal box
- what's the difference?


> 
> therefore you might be picking some noise, if not from something 
> radiactive in close to rx module, than from cosmic radiation maybe?

If their geiger counter really works that means
if a particle strikes Ronja PIN diode it could make
a packet dropout. Can someone try putting something radioactive
next to the PIN and run a packetloss test?

Karel
> 
> Anyway I can confirm that simple darlington transistor as used in
> http://www.techlib.com/science/ion.html#Experimenters%20Chamber
> can sense radioactive source.
> 
> regards,
> s.
> 
> _______________________________________________
> Ronja mailing list
> Ronja at lists.pointless.net
> http://pointless.net/mailman/listinfo/ronja



From discover at fly.srk.fer.hr  Fri Feb 27 11:26:53 2009
From: discover at fly.srk.fer.hr (Silvije)
Date: Fri, 27 Feb 2009 12:26:53 +0100 (CET)
Subject: [Ronja] Progress report
In-Reply-To: <17406143.1235649182274.JavaMail.root@viefep13>
References: <17406143.1235649182274.JavaMail.root@viefep13>
Message-ID: <Pine.LNX.4.64.0902270912380.2256@fly.srk.fer.hr>



On Thu, 26 Feb 2009, Karel Kulhavy wrote:
> The old RX is also a prebiased pin diode in an enclosed metal box
> - what's the difference?

Difference is in voltage I guess. Lower voltage in first rx allows
some ions to recombine so giving less noise current while higher voltage
sweeps ions faster to the "ion chamber electrodes" so they cannot
recombine thus giving it probably somewhat higher noise current.

Probably all this is of negligable significance, but I just wanted to
point out the possibility ..

s.