- This topic has 6 replies, 4 voices, and was last updated 3 years, 8 months ago by
.
-
Posts
-
Is there a way to mess with the wave shape of the LFO in the mini-me? I absolutely love the pedal and I added a vibrato switch that just lifts R14 to cut the dry signal, nothing special that hasn’t already been done. The problem is, with the dry signal cut the wave shape is obviously much more pronounced and sounds very “chunky” square wave like. Is there any way to smooth out the waveform? It sounds great and I really enjoy the tones I get from the “vibrato” dry setting but it sounds like a square wave version of a boss VB2. I was thinking it may be as easy as a simple component change in the LFO (hopefully) but I really don’t know the interworking of how this LFO works so I don’t even know where to start looking. Any help would be appreciated thanks!
From what I can make of the circuit, the CD4047 IC is a logic device, meaning it is not going to deliver a sine wave for smoother transition between hi and low states. It is a clock circuit, rather than an LFO circuit, which cannot have a shaped wave. It can deliver different pulse widths, but I’m not sure if simply changing the pulse-width, (pulse-width-modulation) will do what are seeking.
IC4 appears to be the “LFO” that drives the 4047, but regardless of what wave shape the IC4 circuit delivers, 4047 is going to “gate” its output as digital pulses and not deliver a true LFO, wave-shapeable signal.
I’m not terribly familiar with these newer BBD circuits, but maybe Barry, Wilkie or someone else will chime in and have something different to say.
All the best.
+1 Cybercow. You are correct. The circuit topology of this circuit is using a LFO to clock the digital CD4047. The output is a square wave and probably could not be modified since it works in conjunction with the MN3007.
To produce square, triangle and sine wave shapes, a function generator design is required such as shown here:
Obviously, this requires additional components to be added to basic LFO designs.
SInce the GPCB MINI-ME circuit uses the 4047 and 3007, I do not see an easy way to add wave forms.
Wilkie – thanks for the +1 and clarification. And I appreciate the schematic you shared for the sig-gen. I’d like to find a similar circuit the both displays and controls the frequency and amplitude. Based on the schematic you shared, looks like ‘circuitstoday.com’ is a good place to start. I know I could throw money at manufactured sig-gen, but those funds are scarce for me and I have parts and enclosures and am sure I can locate some inexpensive meters. Thanks again Wilkie.
I found a working model on ebay for around $35. I mostly use the sine wave anyway.
There exists an XRxxxx function generator chip. 0.01Hz to 1Mhz? outputing Sine, Sq, and Triangle. complete circuit will fit in a 125b box along w the mini me. Aliexpress sells the complete kit 4 about $2.00 American. bought several a few years back for just this kink of project.
- You must be logged in to reply to this topic.