--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Bengt,
>
> AH! 1K8 = 1800 ohms.  I see.  My mistake.  But that makes the max current even less.
>
> I don't follow your formula for R1.
>
> The maximum current you can get through a 1800 ohm resistor with full 24V is
>
> I = 24/1800 = 13ma
>
> So the transistor base current will be less than this (because of 2 voltage drops and because some of the current will flow through R5 instead).
>
> 13ma x 25 = 325ma
>
> If you change to a transistor with a min HFE of 100 you should be ok for 1A.
>
> Or you might consider a MOSFET instead. Something like:
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=DMP4050SSD-13CT-ND
>
> (set R1=R5=2K)
>
> TK
>
>
>
>
>
> ________________________________
> From: bsjoelund <cnc@...>
> To: DynoMotion@yahoogroups.com
> Sent: Mon, June 7, 2010 12:31:22 AM
> Subject: [DynoMotion] Re: Kanalog JP13
>
>  
>
>
> Hi Tom,
> Thanks for your comments, new updated file.
>
> #1 I did not write pin numbers as it was too obvious for me :), now in schematics.
> #2 Did not find correct data obviously
> (R1 = Supply Voltage / ( Max Current Required / Minimum HFE * 1.3 )( 24V / (1 / 100 * 1.3) )
> #3 No font problem, we type 1800ohm as 1K8 (1R8 for 1,8ohms 1M8 for 1,8 Megaohm)
> 4# Of course, I stand corrected (too late at night in CAD :) )
>
> Cheers Bengt
>
> --- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@> wrote:
> >
> > Hi Bengt,
> >
> > Looks pretty good.  But a few minor comments:
> >
> > #1 - I think the pinout for Kanalog JP13 is wrong.
> >
> > There are 2 isolated pins for each opto.  So all the negatives (even pins 2,4,6,8) should be connected to your 24V ground.  And the odds (1,3,5,7) should go to your resistors. 
> >
> > See:  http://www.dynomotion.com/Help/SchematicsKanalog/JP13.PNG
> >
> > #2 - The circuit might not be capable of driving 1 Amp.  The spec I found shows a minimum current gain of 25.  Since the 1K ohm resistor will drive the transistor base with about 23ma.  Then 23ma x 25 = 575ma.
> >
> > #3 - something wrong with the font.  1K (ohm) came out as 1K8 on my computer.
> >
> > #4 - very minor point - usually circuits are drawn with currents flowing down, so I would have flipped the transistor symbols horizonatally.
> >
> > Thanks!
> > TK
> >
> >
> >
> > ________________________________
> > From: bsjoelund <cnc@>
> > To: DynoMotion@yahoogroups.com
> > Sent: Sun, June 6, 2010 3:29:45 PM
> > Subject: [DynoMotion] Re: Kanalog JP13
> >
> >  
> > Hi Tom,
> > Just uploaded pdf file into files section, Bengt's Beacon adapter.
> > Can you just have a look and say if this is OK to use?
> > Cheers Bengt
> >
> > --- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@> wrote:
> > >
> > > Hi Bengt,
> > >
> > > BTW why don't you use one of the relay driver outputs?
> > >
> > > That link you sent didn't specify anthing about the needed drive. Sink? Source?
> > >
> > > Yes you could probably use an external transistor in a darlington configuration.  See attached:
> > >
> > > TK
> > >
> > >
> > >
> > >
> > > ________________________________
> > > From: bsjoelund <cnc@>
> > > To: DynoMotion@yahoogroups.com
> > > Sent: Sat, May 22, 2010 12:44:43 PM
> > > Subject: [DynoMotion] Re: Kanalog JP13
> > >
> > >  
> > > Hi Tom,
> > > Maybe it is better to hook up some small driver for my purpose, these LED's in the Beacons are specified to 24DC 30mA. What do you suggest to use? Small schematics perhaps?
> > > Cheers Bengt
> > >
> > > --- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@> wrote:
> > > >
> > > > Hi Bengt,
> > > >
> > > > Sorry we intended the limit to state 25ma everywhere.
> > > >
> > > > This is a conservative specification based on the worst case part and with margin.ÃÆ'‚ ÃÆ'‚ The opto devices have a wide variation in CTR (current transfer ratio) of 100-600%
> > > >
> > > > The Absolute Max rating for the device is 50ma and 100mw.ÃÆ'‚  If you test that the on current is 30ma or less and the voltage drop across Kanalog's opto is less than 2.5V (2.5V x 30ma = 75mw).ÃÆ'‚  Then you should be ok.
> > > >
> > > > TK
> > > >
> > > >
> > > > ÃÆ'‚ 
> > > >
> > > >
> > > >
> > > > ________________________________
> > > > From: bsjoelund <cnc@>
> > > > To: DynoMotion@yahoogroups.com
> > > > Sent: Sat, May 22, 2010 10:08:21 AM
> > > > Subject: [DynoMotion] Kanalog JP13
> > > >
> > > > ÃÆ'‚ 
> > > > Hi,
> > > > Confusing as document says two different values.
> > > >
> > > > Text below the picture says 80V 50mA
> > > > and furhter down JP13 text says 80V 25mA
> > > >
> > > > I would like to use my Telemecanique Illuminated Beacons, 24V 30mA
> > > > http://datasheet.octopart.com/XVB-C2B8-Telemecanique-datasheet-510161.pdf
> > > >
> > > > So what say you, is it OK to load with 30mA?
> > > >
> > > > Cheers
> > > > Bengt
> > > >
> > >
> >
>