Living expenses have to come from somewhere. If you use the time to graduate faster, instead of working to generate weekly income, in some cases you can come out ahead overall. Details vary, but it's not obvious that it's a bad deal.
Based on the breakdown, it sounds like she has $100 leftover per month. That pretty much sounds like "liability" money to me. Barely much to dispose of.
The average student loan debt is $38k. If you borrow $100 extra per month, and defer your first payment till the month you graduate, your extra burden is $5300 or so or about 14%. The average borrower takes 20 years to pay off the debt. They’d pay it off 2 years earlier without this extra expenditure.
Okay, but this isn't a 4 year university loan. It's a masters program after she went back to school.
Someone pursuing a masters is much more likely to have a plan on how to turn that degree into better career progression or other opportunities. Especially a masters student who spent time in industry.
And honestly 5k loans to pay off 2-4 years later is about as good a loan debt as you're going to get. Paying off thst debt is more about having a career plan by that time than penny pinching for as low as loan value as possible.
I think most students in America have loans. For me, and everyone I knew, there was a credit balance after the school got paid and that money was put into your bank account.
Don't forget you have to buy books, etc., and they cost "a couple of hundred dollars" too.
When I was an undergraduate I was definitely on a knife's edge, but I also often had cash in the bank because I got a big cash infusion annually. I just had to live off a very strict budget at that time to make sure the money would last.
I wouldn't have wanted to rely on this service when I was a student, especially at that cost, but in a pinch I could see situations where it would make sense.
> It's weird because CMRR is listed in decibels but it's absolutely a DC spec.
If you get the Franco book equation 5.27 (my edition is the 3rd) explains why they do that. Long story short: It's a convenient form when CMRR = dVcm/dVos due to the orders of magnitude involved.
The moral is that you have to be careful. The ratio and decibels giving CMRR might not be the same as quoted for a given closed loop gain at a given frequency of interest.
Technically you probably could do it externally in most cases but it would require a bunch of extra stuff, and be a pain, so usually it's best to use the stuff built into the amplifier itself.
I've seen designs that use a Chopper Op-Amp to actually auto-zero a power-OpAmp, effectively transferring the low Vos characteristics to a different OpAmp with completely different characteristics.
If the op-amp has a stable Vos I feel like maybe you could zero it by hand with a trimpot? You just need a button to short the inputs together while you're trimming it.
That's only rated good to 5 μV, according to the datasheet. You'd probably be better off with a non-auto-zero LM324B, whose worst-case Vos is rated at 3 μV IIRC. Of course it didn't exist at the time (01989) which is why National made the LMC669.
But the potential advantage that building a chopper (or auto-zero) out of ordinary opamps would be that you don't need to source, order, and await specialized chips. A long-discontinued bolt-on auto-zero for a regular opamp has almost all the disadvantages of just buying an auto-zero opamp.
On CMRR, in some mathematical treatments it's modeled as a change in offset voltage with respect to common mode, which indirectly effects output voltage of course so at the end of the day it's the same result. (See: https://www.google.com/books/edition/Design_With_Operational... highly recommended )
It's also odd that the 741 was dismissed, as it should be, but the TLV9301 was not recommended. This part is specifically called out on TI's 741 page as what to use instead in 2025. Not only does it perform better in basically every possible spec, it's also a drop in replacement for most, if not all, applications.
