Highway 89 failed attempt

[csj]

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[Joe Davisson]

Q2's collector should be jumpered to +9v. Ideally, Q1 and Q3's collectors should be at 4.5v, although 5.0v isn't too far off the mark. This varies with transistor gain, so adjust the collector resistors on Q1 & Q3 to obtain 4.5v. Leave Q2 alone.

Also, make sure you have the latest schematic, one of the early ones had a mistake.

Before building it permanently, it would be worth ordering the right transistors (they used to be like 5 cents each), then breadboarding to make sure the voltages are right. Transistor gains should be 500-600. I don't think the caps or other parts will matter though.

If you have to use the RS transistors, find the highest gain ones. Gains under 500 may benefit from this alternate biasing scheme:

Q2: 3.3M/1M bias
Q3: 10k collector, 2.2k emitter

Again, adjust the collector resistor slightly until it's close to 4.5v. Hope that helps out. Mine has a sound similar to Doug's clip (besides the good playing Hope that helps out some...

-Joe

[csj]

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[Doug H]

Q1 collector won't be 4.5v. It's 5 or higher IIRC. As Joe mentioned, use higher hfe transistors. The hfe of my 2n5089's are around 800. I don't know how it sounds with lower gain transistors, but you will need all the gain you got with this circuit.

Doug

[DaveTV]

Hi everybody. I'm about to build a Hwy 89 myself (parts are ordered and on their way).  How do I know if I've got an older version of the schematic? What are the mistakes to look for?

[Doug H]

The .68u treble-leak cap should be wired from the Q1 collector to the gain pot wiper.

Doug

[DaveTV]

Thanks Doug. Looks like I've got the right one then. I'm definitely planning on breadboarding this one to make sure all the voltages are correct.

[Nick123]

Excuse  me  guys,  I  can't  find  schematic  of  HIghway89  anywhere.
I  manage  to  find  only  perfboard  of  it.