Trem is Ba-a-a-a-ck! And Other Growls From The Cave...

[smallbearelec]

http://www.smallbearelec.com/Updates.htm

[Paul Perry (Frostwave)]

Looks like nice work on the Trem, Steve! A really good trem is astonishingly hard to make, compared to most other effects. Looks like you nailed it.

[RDV]

Let's have a sample! Let's hear it.

RDV

[smallbearelec]

I just posted a few at the beginning of the article. #1 and #2 are both triangle-wave mode, but #2 is one idea of an off-kilter modulation. Both use the bias pot to fill in some of the dead space between beats. #3 is square-wave mode with no bias--more percussive.

I hope that other people will confirm what I have noticed: Built as shown, the Trem Bear is Very Quiet in between beats. Two features of the construction that I am sure contribute to this are the physical separation of LFO and Modulator, and the separate ground planes brought together at the negative power supply input (R. G. Keen's suggestion in a long-ago post.) Someone else here (don't recall who) mentioned the use of a capacitor to damp the edges of the square wave on the 555. I had done this on the original because it seemed logical, but I only used .01 mf.; this turns out to be not enough to forestall ticks at heavy depth settings. The .68 mf. in this version is very effective.

[rockgardenlove]

Thanks for visiting, and for your orders! I will add other goodies from your (long!) list of suggestions in the second half of the year.

Lets make the list a little bit longer!  How about some cheaper E-H sheet metal boxes!  That would be SWEEEET!

[Processaurus]

Looks really good, Steve.  I wasn't totally clear from reading your article what the speed 2 and bias controls do,  basically which one controls the duty cycle, and what does the other do?  Also, does the duty cycle affect the triangle wave (as well as the square wave) to give sawtooth waves at each extreme?

Thanks again for the article, and good luck this year with the cave.

[smallbearelec]

I wasn't totally clear from reading your article what the speed 2 and bias controls do.

The duty cycle depends on the settings of both Speed 1 and Speed 2, and D1 if you switch it in. The bias control doesn't affect the duty cycle of the LFO--it sets the amount that Q2 is "on" while the added current from the LFO is at minimum.

Also, does the duty cycle affect the triangle wave (as well as the square wave) to give sawtooth waves at each extreme?

The duty cycle settings do affect both triangle and square. I don't have a scope, so I'm basing this statement on having listened at many settings. I'd welcome comment from a builder who scopes the thing and can tell us what is really happening.

[Paul Perry (Frostwave)]

I don't have a scope,

:icon_eek:CRASH! (sorry, just fell off my chair....) Well, there's proof that if you know what you are doing, you can do it without a scope! I think I better keep mine, though

[smallbearelec]

:icon_eek:CRASH! (sorry, just fell off my chair....) Well, there's proof that if you know what you are doing, you can do it without a scope! I think I better keep mine, though

I think this kind of low-speed, not-too-complex thing is about the outer limit of what one can reasonably do without the o'scope. I did, long ago, learn the basics of using one, and I expect to make the investment (especially since they have become so relatively inexpensive!) and get back into it.