Current source [Result]

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=A0 =A0 =A0 |

=A0 =A0 =A0|

=A0 =A0 =A0|

=A0 =A0 =A0 |

=A0 =A0 =A0 |

=A0 =A0 =A0 =A0 |

=A0 =A0 =A0 =A0 |

=A0 =A0 =A0 =A0 |

=A0 =A0 =A0 LOAD

=A0 =A0 =A0 =A0 |

=A0 =A0 =A0 =A0---

=A0 =A0 =A0 =A0///

Not at all- the Howland is based on a NIC, this is not. Errors are significantly less than any opamp vcs. It is a bootstrap, and a single component solution.

Reply to
Fred Bloggs
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Usually if the offset current is similar to the bias current, that's an indication that there is no point in trying to balance the DC paths looking out from the inputs, and it can easily be counterproductive (decrease phase margin).

I don't like adding extra parts when reliability is a primary concern. This one might be marginally improved at extremes but I think i'd rather just stay within the data sheet guaranteed limits or pick a better part.

It might be justified in some high-EMI situations- it's kind of a black art, but making things more symmetrical can reduce susceptibility dramatically, and it's a particular concern with bipolar parts such as the LT1012.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
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Reply to
Spehro Pefhany

You only rely on NoScript? That would be scary ...

I never have any issues with properly designed company web sites. Problems arise when sites want to play dicey stuff. Sometimes I come across a not properly designed web site. The strange coincidence is that those are companies that aren't all that important anyhow. The Digikeys and ON-Semis of this world don't do that stuff.

--
Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

Don't trust LTSpice for everything. For example, transistor e-b junctions do not have reverse break down in simulation. I put +1000v to the emitter of a 2N3904 with the base grounded. It had 1uA leakage at that voltage!

Take the advice of experienced people here. They have done this before.

Reply to
John S

so...

I block javascript also, except for known good sites. At home I'm, of course, behind a hardware firewall. On-the-road, as I am now, I take no risks, but also carry no risky info on the laptop. ...Jim Thompson

[On the Road, in New York]
--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

don't work for me either

Reply to
David Eather

Your breath condenses pure water; only dirty water is of interest In causing stray conduction.

Trust not a test that will change after dust settles, unless you plan to skip town after delivery of the goods.

Reply to
whit3rd

How do you build a diffamp with a gain of 1, with picoamp input current and high common-mode rejection? A full schematic would be helpful.

John

Reply to
John Larkin

??? I see an animated ad, same one in both references..

Reply to
Robert Baer

On a sunny day (Sun, 24 Jul 2011 15:57:34 -0700) it happened John Larkin wrote in

By going via an other network, some sites provide web browser ftp access:

formatting link

It will list your directory, and then I can download the picture, after looking for it in the alphabatically sorted listing.

I dunno what is the problem, it is either Vodafone network, or your ISP blocking Vodafone network, or both. Vodafone denies they are blocking, but that does not mean anything, as there is such a thing as a 'stateful firewall' they use (if I remember the term correctly), and technical helpdesks these days are total jokes. For example I asked (when I was still on the KPN network), if IP address would change, and they said 'no', but the person obviously did not know the difference between an IP address and an email address. The IP changed, and I forgot the email address password (never used theirs), anyways KPN was BAD, good network, but BAD customer support. I got a lot of money back after writing some letters to them. They (KPN) also got political headwind, and have to lay of a large part of their workforce. Vodafone gave me a big discount, I pay very little a month now for fast mobile access. They want to keep their customers.

Reply to
Jan Panteltje

n
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=A0"The Journey is the reward"

1562,4,00.html

Follow the NEXT to What's All This Femtoampere Stuff. It has some Bob Pease schematics that are neatly drawn.

Reply to
Wanderer

That's cool.

John

Reply to
John Larkin

It's similar but the typical value is still higher.

Well, if there's only one lytic or tant in the system that'll dominate the MTBF anyhow so one or two extra resistahs don't make much of a difference. Not using them is like leaving money on the table.

In applications like this you have to. I'd even add GHz filters from Murata or similar. Over in France they have GSM exclusively AFAIK and that is quite brutal on opamp inputs. That is why a lot of Europeans make sure they don't park their cell phones on the stereo.

--
Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

so...

Same here. But one must be careful because eventually you will have to work on some hot circuit even if you never store in on the HD.

But anyhoo, if a web site won't let me on unless I turn safety features off then I will not grace it with my presence :-)

--
Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

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=BD =EF=BF=BD =EF=BF=BD Courier.

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BDVCS

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD| \

=EF=BF=BD>-----|- =EF=BF=BD\ =EF=BF=BD =EF=BF=BD + Vin -

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD| =EF=BF=BD =EF=BF=BD|

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BDIA =EF=BF=BD|G=3D1 |-----[Rcs]---.

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD| =EF=BF=BD =EF=BF=BD|= =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD |

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD----|+ =EF=BF=BD/ =EF=BF=BD =EF=BF=BD =EF= =BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD|

=BD =EF=BF=BD =EF=BF=BD | =EF=BF=BD =EF=BF=BD| / =EF=BF=BD =EF=BF=BD =EF=BF= =BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD|

=BD =EF=BF=BD =EF=BF=BD | =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD= =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD |

=BD =EF=BF=BD =EF=BF=BD | =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD= =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD |

=BD =EF=BF=BD =EF=BF=BD '-----------------------+

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD = =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD |

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD = =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD |

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD = =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD |

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD = =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD LOAD

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD = =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD |

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD = =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD---

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD = =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD///

Something like this for single supply - I may have overlooked something- not going to spend a lot of time studying the datasheet:

Please view in a fixed-width font such as Courier.

. . . . \ . | \ +Vsupply . | \ | . Vc >--------|- \ | . | \ | . | \ | . NC --|RG | . | \ Vref-Vc . | \ + - . Vref >--------|REF > ---[Rcs]---+------>

. | / | . | AD8220/ | IL ->

. | /| | . NC --|RG / | | . | / | | . .------|+ / ---- | . | | / / / / | . | | / | . | | . | | . '------------------------------' . .

Reply to
Fred Bloggs

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? ? ? ? |

? ? ? ? |

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OK, that should work, but the amp V- supply should be a little negative so the whole thing works down to ground.

AD8220 is a bit expensive for production, and bias current is a tad high; it's a jfet.

John

Reply to
John Larkin

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Reply to
Fred Bloggs

On a sunny day (Sun, 24 Jul 2011 13:50:22 -0700) it happened "Jure Newsgroups" wrote in :

Nice story, that air capacitor that gets discharged by cosmic rays and other radiation: I have a radiation meter that uses an air filled chamber type capacitor that gets charged to a high voltage with a one transistror converter from 1.5V, and has an eklectrometer type vane that then move one way. When radiation (ionisation of the air) happens, the capacitor slowly discharges and then at some point the vane moves back and touches a contact that sounds a buzzer. It uses a double triode (tube) to drive a meter to show the radiation too. The advantage is that it normally uses no power in alarm mode, only when the vane triggers the buzzer. Bought it for 10 Euros surplus.

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page 11 for diagram IIRC, this is in German and 2.5 MB

Reply to
Jan Panteltje

radiation:

gets charged to

eklectrometer type vane

and then at

The classic dosimeter is a metal tube with a frosty glass at one end and a lens at the other. A fiber is visible against a graticule. It's charged and bends to the "0" mark, and discharges and moves up the scale as radiation ionizes the gas inside. Full scale is often a lethal dose. There's a contact button bellows thing on the outside to recharge it; pressure moves it in, closing a gap, to contact the insides when it's being recharged.

I built an electroscope a while back, just an inverted V of foil hung over a thread. You charge it, and the V opens up. I figured that if I brought an americium (smoke detector) source near it, I might be able to see it discharge. The vanes slammed together instantly.

Hmmm, I could make a nuclear battery with that source. My Keithley should be able to measure the current. The problem with nuclear batteries is that they generate low currents at very high voltages, ballpark a megavolt, so it's hard to make a dc/dc converter for them.

John

Reply to
John Larkin

On a sunny day (Tue, 26 Jul 2011 09:17:24 -0700) it happened John Larkin wrote in :

radiation:

gets charged to

eklectrometer type vane

discharges and then at

I remember seeing some publication where they used some radioative source on silicon to make a little lever flap up and down, and they wanted to drive some nano gear with it. Perhaps to make one of those nano size robots that peddle through the blodstream to look for problems. That does omit the electronic step, and perhaps have a higher efficiency than driving an electric motor via a converter.

Reply to
Jan Panteltje

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