About possible Babelfish J interest

[Zen Mod]

(psssst!

blatant advertising)

 

[transcendent]

lol, i did search, looks much the same as on your build it's just that the difference between them seems negligible, was wondering if there's a chance of damaging the resistor if the wattage is bit smaller..

 

[transcendent]

Probably overthinking this ordering the 0.6W, thanks for pointing it out !

 

[Russellc]

Most of these resistors are very conservatively rated. Unless a position calling for 1 watt, 3 watt, 5 watt and so on 1/4 is usually adequate, sometimes 1/8 watt. But for better sleep....My F5 boards from Peter Daniels required standing up soldier style (which I did) anything over 1/8 watt.

Russellc

 

[transcendent]

@Russel, thanks for the tip, will take it into account when soldering resistors.


Hey ZM, any news on psu schematics ??

Anyways, started stuffing the board and noticed small mismatch between Q5 transistors you've sent (BC546) and labels that are attached (BC556) - see photo. Let me know if it still OK to go with it.

 

[Zen Mod]

my bad

anyway - these are non-matched - random , so use anything you have in drawer

regarding schematic of PSU , same applies as in Babelfish M25, SissySIT - general building tips and tricks , post #113

 

[transcendent]

No problem, found couple BC556 options, one - 80V 0.2A 0.5W, other - 65V 0.1A 0.5W. Guess both would work.

BTW, I had to pick different values for few resistors (due to unavailability), am I ok staying in 10% threshold?

 

[Zen Mod]

which ones?

why hurry?

 

[transcendent]

which ones?

R17-18 - 5.1k got 5.6k
R22-23 - 1.5r got 1.6r

why hurry?

well, the availability might never be there anyways, i got it in lower wattage so might play around by connecting in parallel or in series to get it right if it's important to have exact values

 

[Zen Mod]

5K6 instead of 5K1 ok , and even better putting one 5K6 and another 4K7

R22, R23 - these are 1K5 , not 1R5

you can use 1K6

 

[transcendent]

R22, R23 - these are 1K5 , not 1R5

I should probably do this in the morning... It is 1K5 in the list I have.

Thanks for checking anyways, I should be good to go with what I have then.

 

[transcendent]

Got few questions on components:
1) TP2 trimmer resistor in BOM is 50ohm, I got 20ohm version - is it sufficient?
2) C5 - no silver mica can be found here.. do you recommend using regular multi-layer ceramic or SMD on custom legs?

 

[Zen Mod]

1. 20R is OK for TP2 - goal is to have approx 10mA through input LTP ..... so ...... R10 can be 47 to 56R , ref. to schm in post #49

2. 1206 SMD on custom legs is my usual solution ;

 

[transcendent]

Would SMD 0805 work as well? 1206 only starts at 10pF here.

 

[Zen Mod]

not for my old eyes , but yours are hopefully better

 

[transcendent]

ok, just noticed the size, it's not gonna work unless i buy microscope

Few questions:
1) In case using only base PCB, I should only connect AD-AS, instead of N1-N2 right?
2) Is there a good reason placing transformers in front of the case and wiring through the bottom baseplate? Looks easier to have them in the back with less wiring.

 

[transcendent]

OK, got most of the parts in the PCB, except that C5 position and the LED's (5mm does not fit there BTW).. did I miss anything?

 

[Zen Mod]

3mm leds

green

observe orientation - all LED anodes are looking at GND

 

[transcendent]

observe orientation - all LED anodes are looking at GND

Looking at schematics top row LED anodes looks other way around... could you confirm I am wrong?

 

[Zen Mod]

stripe/ring on body is cathode

another end is anode

anodes are looking at GND