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Junebug queries

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New Member
Some questions for the JuneBug, but before that, shouts to William for a simple and great design, please keep it up!


1. U5V and +5v panes are different?
If they are not, then why are they marked differently :-(

2. Why is there a U5V,GND and +5V,GND on the same 16 pin header CON3?

3. What does VPP_FB, T_FB, TGT_N, TGT_P mean?

4. I have a few 1N5819 (Vf = 0.6V), so can I use them to replace the 1N5817 (Vf = 0.4V)?

5. Could a 1N4148 be used?

6. Could a 1N4007 be used?

Now some involved questions (might be specific to William):

I understand that the FETs, BJTs and the schotkey forms a switching PSU, and the PIC has very specific timings, but can't we replace the FETs with run-of-the-mill PNP and NPN BJTs and get similar rise times by increasing the switching frequency?

This would not only make the kit more hobbyist friendly (a BJT is more likely to be stocked in house than a FET!), but also decrease the system cost (more savings = more parts!)

William, do you have the set of transforms/equations and the calcuations with you using which you arrived at the specification/values for the SMPS?

I am interested in replacing the FETs with BJTs, but if you think that would be stupid, I would rather not waste my time :)


Well-Known Member
The kit includes all the parts no need to substitute. You could use beefier FETs but they must be logic level.
U5V is direct USB power, +5V is switched power.


New Member
That's only the answer to point 1, but that was a big help nevertheless :)

Anyone else can help me out on the other points too?
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