If you use 340/350 you don't need to. It's only when you use some uber-performing "upgrade".
In the S-Leach they only have 1/4 of the 168V rail on each one. That puts them at less than a watt. Still, a little heat sink will improve stability of the q-point.
TO-126 beats TO-5/TO-39 in free air and on infinite heat sink.
IME, the ST version of these parts has always been the best. Higher fT than ON, and better consistency. Cheaper most of the time, too.
Exactly. Therefore I also prefer the TO-126
Nevertheless I would try to get such large of the heathsink, that the temperature on it not more than 30 degrees above ambient temperature (please note: internal ambient temperature inside of the amplifier). Here an interest URL with youtube video about diy of this amp and schematic:
Leach SuperAmp Plans
http://users.ece.gatech.edu/mleach/superamp/circuit.pdf
And another amp site with advices regarded the MJE340/350
A HiFi Power Amp
Concerning the not easy to find SANYO Types 2SA1407/2SC3601 (200V/400MHz ft) or 2SA1479/2SC3789 (300V 70MHz ft) I think you find also a supplier in your country: Here two weblinks for ask
1) http://semicon.eu.sanyo.com/distribution/SemiconductorsMay09.pdf
or 2) this address also responsible for your country:
Name of Distributor : Yleiselektroniikka Oyj
Contact person: Mr. Sauli Nilsson
Address : Luomannotko 6, PL73
02201 Espoo
Finland
Phone : 00358-9 452 621
Fax : 00358-9 4526 2202
e-Mail : ilpo.Hamunen@yeoy.fi
Web site : YEInternational - ETUSIVU
Sales region : Finland, Baltic countries
Product area : Semiconductor, Laser diodes
Please note, not all suppliers of hard to find parts have a website.
requires you to use >=180Vce0 transistors wherever they can see the full voltage during operational conditions. If the transistors are cascoded to never see more than half the full rail voltage then >=100V devices can be used
You also need to look at the current rating at the elevated voltages these transistors will operate at and you must de-rate that current to suit the worst case operational temperature you believe will apply to your situation.
This de-rated SOAR design is absolutely crucial to reliability.
Last edited:
Thank you for trying to help me find the transistors, but i don't live in Lithuania i live in Latvia
Last edited:
Farnell Latvijas Republika | Latvia - pasaules vadošais elektronikas un apkopes, remonta un operāciju produktu izplatītājs.
It is also available in Latvia!
It is also available in Latvia!
So now i have soldered almost all resistors and diodes to the PCB's.
Next im ging to solder are capacitors, but i have few questions about those "mica" capaciors used in leach original design :
Are they some special "high-end" tipe mica condensers, can i use regular mica condensers?
And what to do if i don't have exact nominal?
for example i have:
51pF instead of 47pf
200pF instead of 180pF
Can i use them in my leach superamp PCB's?
Next im ging to solder are capacitors, but i have few questions about those "mica" capaciors used in leach original design :
Are they some special "high-end" tipe mica condensers, can i use regular mica condensers?
And what to do if i don't have exact nominal?
for example i have:
51pF instead of 47pf
200pF instead of 180pF
Can i use them in my leach superamp PCB's?
Will work fine. He recommends mica because they are stable. There are also high stability ceramics but people will still complain about those. There is also polystyrene or polypropylene.
The key element here is that they must be stable with temperature/voltage changes as they are used for either compensation or filtering, so their values must not change much. They should also be tight tolerance.
The key element here is that they must be stable with temperature/voltage changes as they are used for either compensation or filtering, so their values must not change much. They should also be tight tolerance.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.