Forums

Again with an oops.

Started by George Herold October 16, 2018
I semi-disabled the output of my opa2134 today.  
Output had right sign at rail, but not enough current.  

Crappy ascii.
        |\
 v-ref--|-\            don't zener base, diode
        |  >--R_5k--+--|<--gnd 
  FB----|+/         |
        |/           >| (pnp 450V)
                      |--gnd             Gnd
                     /|                  |
                    |                    R 20k(?)
                    +--+----+            |
         12V zener  Z  |    R 100        +-->FB              
                    ^  R 5k |            |
                    +--+    |            R 1Meg
                       |    G            |
              -HV------S________D--------+--->load
                         N-FET 

There are 1-10 nF caps on a bunch of the nodes and LND150s as 
current limits (HV in and load out.)  
I fryed my penultimate* nfet (more on order.) 

One thing I was thinking is all my lnd150's are unipolar, 
(so when things go backwards it's easy)
and bipolar might be better.

George H. 
*using penultimate, makes life worth living. :^)   
           
On Tue, 16 Oct 2018 16:51:20 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>I semi-disabled the output of my opa2134 today. >Output had right sign at rail, but not enough current. > >Crappy ascii. > |\ > v-ref--|-\ don't zener base, diode > | >--R_5k--+--|<--gnd > FB----|+/ | > |/ >| (pnp 450V) > |--gnd Gnd > /| | > | R 20k(?) > +--+----+ | > 12V zener Z | R 100 +-->FB > ^ R 5k | | > +--+ | R 1Meg > | G | > -HV------S________D--------+--->load > N-FET > >There are 1-10 nF caps on a bunch of the nodes and LND150s as >current limits (HV in and load out.) >I fryed my penultimate* nfet (more on order.) > >One thing I was thinking is all my lnd150's are unipolar, >(so when things go backwards it's easy) >and bipolar might be better. > >George H. >*using penultimate, makes life worth living. :^) >
How much -HV voltage and current? -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Tuesday, October 16, 2018 at 8:33:42 PM UTC-4, John Larkin wrote:
> On Tue, 16 Oct 2018 16:51:20 -0700 (PDT), George Herold > <gherold@teachspin.com> wrote: > > >I semi-disabled the output of my opa2134 today. > >Output had right sign at rail, but not enough current. > > > >Crappy ascii. > > |\ > > v-ref--|-\ don't zener base, diode > > | >--R_5k--+--|<--gnd > > FB----|+/ | > > |/ >| (pnp 450V) > > |--gnd Gnd > > /| | > > | R 20k(?) > > +--+----+ | > > 12V zener Z | R 100 +-->FB > > ^ R 5k | | > > +--+ | R 1Meg > > | G | > > -HV------S________D--------+--->load > > N-FET > > > >There are 1-10 nF caps on a bunch of the nodes and LND150s as > >current limits (HV in and load out.) > >I fryed my penultimate* nfet (more on order.) > > > >One thing I was thinking is all my lnd150's are unipolar, > >(so when things go backwards it's easy) > >and bipolar might be better. > > > >George H. > >*using penultimate, makes life worth living. :^) > > > > How much -HV voltage and current? >
HV is ~180V in and ~100 V out at the moment. Currents are low, 1mA in and 100uA out. The FET is only spec'd for 200V, I've got some ~500V parts on order. I blew it by f'ing around with the load. (not really sure.) George H.
> > -- > > John Larkin Highland Technology, Inc > picosecond timing precision measurement > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com
George Herold wrote...
> > I semi-disabled the output of my opa2134 today. > Output had right sign at rail, but not enough current.
35mA typ capability.
> |\ > v-ref--|-\ don't zener base, diode > | >--R_5k--+--|<--gnd > FB----|+/ | > |/ >| (pnp 450V) > |--gnd Gnd > /| | > | R 20k(?) > +--+----+ | > 12V zener Z | R 100 +-->FB > ^ R 5k | | > +--+ | R 1Meg > | G | > -HV------S________D--------+--->load > N-FET
Assuming your NFET can turn on at say 4V, why can't the opa2134 drive the 5k resistor to say 5 volts? -- Thanks, - Win
On Tue, 16 Oct 2018 18:10:56 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>On Tuesday, October 16, 2018 at 8:33:42 PM UTC-4, John Larkin wrote: >> On Tue, 16 Oct 2018 16:51:20 -0700 (PDT), George Herold >> <gherold@teachspin.com> wrote: >> >> >I semi-disabled the output of my opa2134 today. >> >Output had right sign at rail, but not enough current. >> > >> >Crappy ascii. >> > |\ >> > v-ref--|-\ don't zener base, diode >> > | >--R_5k--+--|<--gnd >> > FB----|+/ | >> > |/ >| (pnp 450V) >> > |--gnd Gnd >> > /| | >> > | R 20k(?) >> > +--+----+ | >> > 12V zener Z | R 100 +-->FB >> > ^ R 5k | | >> > +--+ | R 1Meg >> > | G | >> > -HV------S________D--------+--->load >> > N-FET >> > >> >There are 1-10 nF caps on a bunch of the nodes and LND150s as >> >current limits (HV in and load out.) >> >I fryed my penultimate* nfet (more on order.) >> > >> >One thing I was thinking is all my lnd150's are unipolar, >> >(so when things go backwards it's easy) >> >and bipolar might be better. >> > >> >George H. >> >*using penultimate, makes life worth living. :^) >> > >> >> How much -HV voltage and current? >> >HV is ~180V in and ~100 V out at the moment. >Currents are low, 1mA in and 100uA out. > >The FET is only spec'd for 200V, I've got some ~500V parts >on order. I blew it by f'ing around with the load. >(not really sure.) > >George H.
You could use my high-voltage optocoupler thing. Much simpler. Variation on this: https://www.dropbox.com/s/pbdcg3fgrc0xyfi/HVamp.JPG?raw=1 -- John Larkin Highland Technology, Inc lunatic fringe electronics
On Tuesday, October 16, 2018 at 9:30:53 PM UTC-4, Winfield Hill wrote:
> George Herold wrote... > > > > I semi-disabled the output of my opa2134 today. > > Output had right sign at rail, but not enough current. > > 35mA typ capability. > > > |\ > > v-ref--|-\ don't zener base, diode > > | >--R_5k--+--|<--gnd > > FB----|+/ | > > |/ >| (pnp 450V) > > |--gnd Gnd > > /| | > > | R 20k(?) > > +--+----+ | > > 12V zener Z | R 100 +-->FB > > ^ R 5k | | > > +--+ | R 1Meg > > | G | > > -HV------S________D--------+--->load > > N-FET > > Assuming your NFET can turn on at say 4V, why can't the > opa2134 drive the 5k resistor to say 5 volts? > > > -- > Thanks, > - Win
Right, I works fine... but f-ing around down stream I somehow fried the Nfet and then the output drive of the opamp. I'm not sure how. I need some more prophylactics. George H.
On 10/17/18 9:33 AM, George Herold wrote:
> On Tuesday, October 16, 2018 at 9:30:53 PM UTC-4, Winfield Hill wrote: >> George Herold wrote... >>> >>> I semi-disabled the output of my opa2134 today. >>> Output had right sign at rail, but not enough current. >> >> 35mA typ capability. >> >>> |\ >>> v-ref--|-\ don't zener base, diode >>> | >--R_5k--+--|<--gnd >>> FB----|+/ | >>> |/ >| (pnp 450V) >>> |--gnd Gnd >>> /| | >>> | R 20k(?) >>> +--+----+ | >>> 12V zener Z | R 100 +-->FB >>> ^ R 5k | | >>> +--+ | R 1Meg >>> | G | >>> -HV------S________D--------+--->load >>> N-FET >> >> Assuming your NFET can turn on at say 4V, why can't the >> opa2134 drive the 5k resistor to say 5 volts? >> >> >> -- >> Thanks, >> - Win > > Right, I works fine... but f-ing around down stream I somehow fried > the Nfet and then the output drive of the opamp. I'm not sure > how. I need some more prophylactics. > > George H. >
An LND150 in series with the source of the NFET might help. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
On Tuesday, October 16, 2018 at 7:51:24 PM UTC-4, George Herold wrote:
> I semi-disabled the output of my opa2134 today. > Output had right sign at rail, but not enough current. > > Crappy ascii. > |\ > v-ref--|-\ don't zener base, diode > | >--R_5k--+--|<--gnd > FB----|+/ | > |/ >| (pnp 450V) > |--gnd Gnd > /| | > | R 20k(?) > +--+----+ | > 12V zener Z | R 100 +-->FB > ^ R 5k | | > +--+ | R 1Meg > | G | > -HV------S________D--------+--->load > N-FET > > There are 1-10 nF caps on a bunch of the nodes and LND150s as > current limits (HV in and load out.) > I fryed my penultimate* nfet (more on order.) > > One thing I was thinking is all my lnd150's are unipolar, > (so when things go backwards it's easy) > and bipolar might be better. > > George H. > *using penultimate, makes life worth living. :^)
Oops, scratch all that. I blew out the zener? Not sure how. (well too much power obviously.) George H.
On Wednesday, October 17, 2018 at 11:13:56 AM UTC-4, Phil Hobbs wrote:
> On 10/17/18 9:33 AM, George Herold wrote: > > On Tuesday, October 16, 2018 at 9:30:53 PM UTC-4, Winfield Hill wrote: > >> George Herold wrote... > >>> > >>> I semi-disabled the output of my opa2134 today. > >>> Output had right sign at rail, but not enough current. > >> > >> 35mA typ capability. > >> > >>> |\ > >>> v-ref--|-\ don't zener base, diode > >>> | >--R_5k--+--|<--gnd > >>> FB----|+/ | > >>> |/ >| (pnp 450V) > >>> |--gnd Gnd > >>> /| | > >>> | R 20k(?) > >>> +--+----+ | > >>> 12V zener Z | R 100 +-->FB > >>> ^ R 5k | | > >>> +--+ | R 1Meg > >>> | G | > >>> -HV------S________D--------+--->load > >>> N-FET > >> > >> Assuming your NFET can turn on at say 4V, why can't the > >> opa2134 drive the 5k resistor to say 5 volts? > >> > >> > >> -- > >> Thanks, > >> - Win > > > > Right, I works fine... but f-ing around down stream I somehow fried > > the Nfet and then the output drive of the opamp. I'm not sure > > how. I need some more prophylactics. > > > > George H. > > > > An LND150 in series with the source of the NFET might help. >
Right I've got a few unipolar ones sprinkled around. I was thinking I should make 'em all bipolar. Cause I can afford the 0.6V drop and that gives me twice the protection... both ways. George H.
> Cheers > > Phil Hobbs > > -- > Dr Philip C D Hobbs > Principal Consultant > ElectroOptical Innovations LLC / Hobbs ElectroOptics > Optics, Electro-optics, Photonics, Analog Electronics > Briarcliff Manor NY 10510 > > http://electrooptical.net > http://hobbs-eo.com
On Wed, 17 Oct 2018 11:13:46 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 10/17/18 9:33 AM, George Herold wrote: >> On Tuesday, October 16, 2018 at 9:30:53 PM UTC-4, Winfield Hill wrote: >>> George Herold wrote... >>>> >>>> I semi-disabled the output of my opa2134 today. >>>> Output had right sign at rail, but not enough current. >>> >>> 35mA typ capability. >>> >>>> |\ >>>> v-ref--|-\ don't zener base, diode >>>> | >--R_5k--+--|<--gnd >>>> FB----|+/ | >>>> |/ >| (pnp 450V) >>>> |--gnd Gnd >>>> /| | >>>> | R 20k(?) >>>> +--+----+ | >>>> 12V zener Z | R 100 +-->FB >>>> ^ R 5k | | >>>> +--+ | R 1Meg >>>> | G | >>>> -HV------S________D--------+--->load >>>> N-FET >>> >>> Assuming your NFET can turn on at say 4V, why can't the >>> opa2134 drive the 5k resistor to say 5 volts? >>> >>> >>> -- >>> Thanks, >>> - Win >> >> Right, I works fine... but f-ing around down stream I somehow fried >> the Nfet and then the output drive of the opamp. I'm not sure >> how. I need some more prophylactics. >> >> George H. >> > >An LND150 in series with the source of the NFET might help. > >Cheers > >Phil Hobbs
How about this? https://www.dropbox.com/s/74h878420mt7b1f/HV_Neg_Reg.JPG?raw=1 -- John Larkin Highland Technology, Inc lunatic fringe electronics