Sign in

username:

password:



Not a member?

Search Sci.Electronics.Design



Search tips

design by Keywords

8051 | Amplifier | AVR | CMOS | Converter | DAC | Diode | FPGA | GPS | I2C | IDE | Laser | LCD | MOSFET | Op-amp | Oscillator | Oscilloscope | PID | PLL | PSU | PWM | RFID | RS232 | RS485 | SMPS | Spice | Transformer | Transistor | TTL | USB | VCO

Ads

See Also

DSPEmbedded SystemsFPGA

design | Re: BJTs as ultra low leakage protection diodes


There are 4 messages in this thread.

You are currently looking at messages 0 to 4.

Re: BJTs as ultra low leakage protection diodes - John Larkin - 2009-06-14 16:22:00

On Sun, 14 Jun 2009 16:07:11 -0400, Phil Hobbs
<p...@electrooptical.net> wrote:

>Ebrahim wrote:
>> Phil Hobbs wrote:
><snip>
>>> The diode needs almost no breakdown voltage at all--certainly not 
>>> 100V.  Something like a BFT25 B-C junction (about 0.3 pF) will work 
>>> great. (WDNNS PAD-1!)
>>>
>> ***
>> That's an interesting idea, you actually bootstrapped the first diode. 
>> Are you sure that any diode can do this?  I mean I think I have done 
>> some measurements with 1N4007 and even in ~0 volt, its leakage was high. 
>> I don't remember the exact numbers, though I must find my papers.
>
>Rectifiers intended for 60 Hz applications are very slow, both slow to 
>turn off and (interestingly) slow to turn on.  They also have lots of 
>capacitance.

We make one gadget whose operation involves forward biasing a big P-N
junction diode by 48 volts.

John



Re: BJTs as ultra low leakage protection diodes - Phil Hobbs - 2009-06-14 16:26:00

John Larkin wrote:
> On Sun, 14 Jun 2009 16:07:11 -0400, Phil Hobbs
> <p...@electrooptical.net> wrote:
> 
>> Ebrahim wrote:
>>> Phil Hobbs wrote:
>> <snip>
>>>> The diode needs almost no breakdown voltage at all--certainly not 
>>>> 100V.  Something like a BFT25 B-C junction (about 0.3 pF) will work 
>>>> great. (WDNNS PAD-1!)
>>>>
>>> ***
>>> That's an interesting idea, you actually bootstrapped the first diode. 
>>> Are you sure that any diode can do this?  I mean I think I have done 
>>> some measurements with 1N4007 and even in ~0 volt, its leakage was high. 
>>> I don't remember the exact numbers, though I must find my papers.
>> Rectifiers intended for 60 Hz applications are very slow, both slow to 
>> turn off and (interestingly) slow to turn on.  They also have lots of 
>> capacitance.
> 
> We make one gadget whose operation involves forward biasing a big P-N
> junction diode by 48 volts.
> 
> John

Yeah, but you're insane.

Cheers

Phil Hobbs

Re: BJTs as ultra low leakage protection diodes - Michael A. Terrell - 2009-06-15 02:50:00

Phil Hobbs wrote:
> 
> Yeah, but you're insane.


   You say that like its a bad thing.


-- 
You can't have a sense of humor, if you have no sense!

Re: BJTs as ultra low leakage protection diodes - Phil Hobbs - 2009-06-15 11:22:00

Michael A. Terrell wrote:
> Phil Hobbs wrote:
>> Yeah, but you're insane.
> 
> 
>    You say that like its a bad thing.
> 
> 
Not at all.  John is the most entertaining wild man I know--his 
delusions actually work.

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net