on the patent

its the Vbe TC that is used. 

on the lm334,
it's the IC, and an external diode for the TC equalizing (if you use the example circuit later on to 
balance the TC)



on the patent

figure 3 is the basic example.

fig 1 omits the current mirror.

figure 3 is described in the details section of the patent

figure 4 or 5 has additional balancing.




todo: build figure 20, and test to see what kind of current lowering I can get


todo: build transistor only circuit of this current source, based on schematic in LM334 data sheet.
might need multiple emitter transistor EDIT: I don't think so. they aren't common in standalone packages.
only on ic die. and some are not true multi emitter, but just two bonded leads to the same emitter.

https://en.m.wikipedia.org/wiki/Multiple-emitter_transistor


article in edn covers what bob pease has for a circuit. similar to ti data sheet with transistor, but drives
constant current for an led



current source notes: 09/20/20

st and ti schematic are slightly different, extra base connection on st.
lt schematic is different from those. it adds two mosfets.

as per ken sherrif blog, theres no such thing as a standard part
in electronics, so likely every manufacturer implements the
lm134 differently. Decapping would be useful here...

There is also a concern that ICs allow for different techniques than discrete (but I bet a discrete LM134/334 is still
possible).

issue is that second row of transistors is not activating (the npns)

Further research needed:
check discrete lm741 by evilmadscientist labs and evaluate how they adopted the op amp from its schematic to discrete
components:
https://shop.evilmadscientist.com/productsmenu/762

as discussed here:
https://www.eevblog.com/forum/beginners/555-from-transistors/msg1451815/#msg1451815

and
https://www.eevblog.com/forum/beginners/how-hard-is-it-a-make-a-transistor-opamp-like-lm358-chances-of-working/msg1403648/#msg1403648



Perhaps in the meantime, I could make just an op amp current limit circuit based on 
the diagram in the LT data sheet notes (Page 5, basic theory of operation). Decapping and reverse engineering of a few LM334 would be useful.


if I had $450 I could buy a wafer... 
https://www.digikey.com/products/en/integrated-circuits-ics/pmic-current-regulation-management/734
hah