PIC power supply basics

[shottootto]

Thank you Charlie

I agree, there are far too many pitfalls for comfort and an entry level, off the shelf unit is cheap, tested and probably comes with instructions and notes on different chips.

Thing is, I am kind of inquisitive and DIY helps me understand things better. It is also about the satisfaction in getting a self-built thing to work. As said, I will eventually buy a programmer -
probably December (bonus month), but not until I at least understand the power supply requirements.

It would help me (and probably some other newbies also) if we can get a discussion going here on the 2 power supplies only. Things like: "Vpp is raised to 12V to put the chip into programming/verification mode.
The chip itself generates the required HV pulse during programming." would be helpful. [comments in quote not necessary factual]

I did some more reading. With the "Vdd first" method, Vdd can have 5V all the time. This leaves only Vpp that requires switching. Brings me back to my first question. Is it possible that these home-brew programmers rely on
a capacitor to smooth out the switched 5V to a continuous voltage, or are they using the Vpp first method?
On my contaption so far (Vpp and Vdd from same comms pin), I can see the LED on Vdd switching during transfer. This does not seem right to me. (Unless it's Vpp first).

So my next step is to hard wire Vdd from an external, regulated 5V. Next, I want to see if I can also use external 12V, switched by the comms port via a transistor to Vpp.
Will have to do some reading to get the transistor circuit right. NPN? PNP? and will BJT rise time be fast enough? Another option I am thinking of is a 4066 or similar bilateral switch. Going to look for datasheets on that now.