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Re: [TCML] Eastern Voltage Research staccato board



The design of EVR's PCB is very similar to the original design by Dave Sharpe,
and my modifications, and Steve Ward's schematic at his website.  In Dave's,
mine, and Steve's, boards the bypass switch definitely works correctly.  Dan
of EVR added another timer IC to give an extra pulse variation, that might
have required a change to allow the bypass switch to function properly.  
I don't know, I haven't looked at the schematic.  Should be easy to fix though.
I have one of Dan's boards, but I didn't populate it yet.  I think I remember seeing
the schematic for Dan's board in the past when he was working on the design.


John



-----Original Message-----
From: Steve White <steve.white1@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Wed, Jan 24, 2018 8:54 am
Subject: Re: [TCML] Eastern Voltage Research staccato board

I am satisfied with the way the EVR board works even with its quirks. As you say it is very compact. It does the main job of providing a variable pulse width and PRF. From my understanding of triac operation, a positive DC voltage must be applied to the gate with the return on MT1 in order to allow for CW operation. Looking at the EVR schematic, there is no way that this positive DC voltage can come from it with the bypass switch in either position. I may make some mods to allow a switch to either send the EVR pulsed signal or a +12 volt DC level to the triac gate for CW operation. I only anticipate using the CW mode for troubleshooting operation on the VTTC. The CW mode is also quieter and has a distinct look and sound although it heats up everything much more quickly.

----- Original Message -----
From: "Chris Reeland" <chrisreeland@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, January 23, 2018 10:57:24 PM
Subject: Re: [TCML] Eastern Voltage Research staccato board

Hi Steve,

I bought one of these about a year ago. I still have yet to put it
together. I got it to have a nice compact PCB (current one using is big and
messy) to put in an enclosure. This is good to know about the slight
problem. I will have to dig mine up and look at the schematic out of
curiosity now. I do remember about the bypass position this has. But I will
admit never gave much thought to it because I will never probably use it.
On one of my coils, I have small old knife switch lever to directly bypass,
for me, at the triac it has. I have maybe used it twice. On my current
3-500ZG project, I am not going to bother with this at all.

You will have to decide if you want this feature. And which way to do it.
Add a switch or try to fix the problem it has. I will probably look at the
schematic myself when I get more time and see if it is an easy fix or not.
And get it built also, and tested on a scope. If not easy, I will probably
take this switch off. Since for me I will never use it.

Currently, I have a somewhat similar interrupter built on a breadboard
which is a "working mess". And takes a bit of room. But it works very good
for me. I have "tuned" it up to get it to work the way that I want it using
a scope. All the components was stuff that was on hand, hence the "mess".
Multiples of some, instead of a single to get the values needed. Again,
kind of messy.  But I am also able to easily change this when I want to
change how it is "tuned" for other "effects" on running coil. So I guess
that is why the  EVR one is in the box still...but it is getting time to
try this one out finally.

Sorry I'm not probably much help right now but I wanted to give some
thoughts.
Going to be several weeks before I have a chance to build the EVR one.
Hopefully someone else can help now. I will be watching out of curiosity.

Chris

Sent from my LG V20
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