Quad 405 Replacement Transistors

Manu wrote:

Peux-tu me donner les équivalences actuelles concernant les composanst suivants : - Transistor ZTX504 - Transistor ZTX304 - Transistor BC214C - Transistor 40872 ( sur ton site MJE15031 mais j'ai vu aussi BD244C ? ) - Diode IS902 - diode LR120C

Can you give me actual equivalents for (...) those transistors/diodes?

• For the BDY77 power-transistor in the original schematic (TR9 / TR10), often replaced by the Toshiba 2SD424 in later models, I use the 2N3773. (http://www.onsemi.com/pub/Collateral/2N3773-D.PDF). This is a very"fast" transistor with excellent and overrated specs.
• For the drivers 40872 (TR7 / TR8) I use - excellent - B536 from NEC. The 2SB546A should be an alternative but I did not test it.
• ZTX304 and ZTX504 (several TR's) can be replaced by BC639 and BC640 resp. if necessary. Attention, the connections are different: B/E changed places. There is no reason to replace those transistors if they are not broke. (http://www.fairchildsemi.com/ds/BC/BC640.pdf).
• Diode LR120C is a Zener that stabilises the Opamp power supply. If you replace the Opamp by a Burr-Brown or other modern chip, replace it for a 15 Volt zener. If you keep the old Opamp use a 12 Volt zener.
• For the other Diodes any standard diode like the 1N4002 will do the job.

All Quad transistors & other components are available in the Dada Electronics Webshop.

Stefaan