[sdiy] Thomas Henry VCO-1

[Stewart Pye]

Thanks to those who have replied off list already. I have another question:

I've been looking for some matched PNP transistors for the VCO-1. I 
found these at Mouser for $0.48...

BCM857BS,115
http://au.mouser.com/Search/Refine.aspx?Keyword=BCM857BS%2c115&FS=True 
<http://au.mouser.com/Search/Refine.aspx?Keyword=BCM857BS%2c115&FS=True>

I know they are SMD, but I'm experienced with soldering chips with 
0.65mm pin spacing. My question is will they be good enough for the expo 
converter? Datasheet can be gotten from the link above.

HFE typ 290
HFE matching:
HFE1/HFE2 min 0.9 typical 1
So, worst case if one was 300 the other could be 270. Doesn't sound too 
good. I'm guessing they would usually be closer to 1.

VBE matching MAX 2mV. This seems pretty good.

Would I be wasting my time laying out a PCB for these? I'm planning on 
making a little expo converter PCB with a right angle header so I can 
change them if it doesn't work so well.

Cheers,
Stew.