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71.198.200.53
Well, I guess I could've just as easily titled it 2009. I finally decided to do the mods to my IG-18 square/sine gen.(Greening of the IG-18) and started getting a parts order together. I was wondering if anyone knows of an updated parts list (the original was done in 1971) for upgrading? The parts I'm having trouble locating are listed below;
dual 1 M linear rheostat (needs to be an open circuit @ 0 setting)
1n91 or 1n39 germanium diode (found a source in the UK but the shipping!)
transistors;
2n5687 (mot)
40361 (rca)
40362 (rca)
40408 (rca)
I would imagine that all these parts have a modern sub that can be used. Any assistance would be greatly appreciated.
Follow Ups:
You can use a 1N34 for the germanium diodes. Do an ebay search on 1N34 and you will find US sources.
40361 ----- use 2N2219
40362 ----- use 2N2905
Where are the 2N5687 and 40408 used in the generator? The schematic only shows transistors as Q1, Q2, etc.
Good luck
Phil
Thanks Phil, here's the info related to the 40408;
The added circuit is a simple emitter follower.The transistor I used isn't too critical, so long as it has a Vceo greater than 45.
Regarding the 2n5687;
I increased the current gain of Q3 by converting it into a compound pair/adding another transistor.It should be a high hfe, low noise device with a Vceo of not less than 45V and must be a pnp.
For the potentiometer, check Mouser stock # 31VW601 at Mouser.com
Mouser sells Zetex transistors that might work OK. Look at ZTX651 (npn) and ZTX751 (pnp). They also have a PNP Darlington if you need even more gain -- ZTX705
Hope this helps. I have a IG-5218 with the Walter Morrey "Super Oscillator" mods from Audio Amateur (Issue 4/75) but I think mine needs a little work too.......
Phil
I once also considered just gutting IG-5218 (keeping freq & amplitude switching capabilities) and using the "Ultra-Low THD Oscillator" circuit from the data sheet for the LT1115.
Wow, thanks a million Phil. I'll have to check these other options out. I've got a little time on my hands so this is a good time to do this kinda stuff.
You're welcome and good luck. I'd be interested in learning what you end up doing so if you have some successes, please post them if you can.
thanks
Phil
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