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Author Topic: ti an31 opamp guide component question  (Read 1424 times)

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Offline PH9ZTopic starter

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ti an31 opamp guide component question
« on: November 01, 2018, 08:31:24 pm »
I'm playing around with opamps trying to build the examples from AN31 guide: http://www.ti.com/lit/an/snla140b/snla140b.pdf

My question:  what is q1 in figure 55, same as q1,q2 and q3?
I don't regonize the part.....

regards John
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Offline MasterT

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Re: ti an31 opamp guide component question
« Reply #1 on: November 01, 2018, 09:29:41 pm »
MOSFET.
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Offline Audioguru

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Re: ti an31 opamp guide component question
« Reply #2 on: November 01, 2018, 09:56:59 pm »
Ph9z, I see what is wrong.
The LM102 opamp is obsolete and the 4 terminals Mosfet is also obsolete. Maybe in 1959 a Mosfet had 4 terminals. 
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Offline capt bullshot

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Re: ti an31 opamp guide component question
« Reply #3 on: November 01, 2018, 09:58:11 pm »
Quote from: MasterT on November 01, 2018, 09:29:41 pm
MOSFET.
Yes, but a nowadays quite uncommon variant with bulk bonded out. Bulk as opposite of gate, usually internally connected to source.
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Offline PH9ZTopic starter

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Re: ti an31 opamp guide component question
« Reply #4 on: November 02, 2018, 06:41:51 am »
THX, I will start playing around with a BF511!

Regards John
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Offline Zero999

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Re: ti an31 opamp guide component question
« Reply #5 on: November 02, 2018, 02:35:21 pm »
Quote from: PH9Z on November 02, 2018, 06:41:51 am
THX, I will start playing around with a BF511!

Regards John
That's an N-channel JFET.

What's the supply voltage?

How about the CD4007 or an analogue switch, such as the CD4016?
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