[BUILD] fripholm's TG1 Zener Limiter boards - support thread
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Help Support GroupDIY Audio Forum:
Mmm...this is what I was worried about. Ok, I'll return it and go for a 2 x 25V instead.
Tommia stated in an earlier post that the unit consumes less than 10W - so I think this 2x25V 30VA would be more than suitable?
https://uk.rs-online.com/web/p/toroidal-transformers/6719084
ETA: I'll be running two boards from a single PSU.
Tommia stated in an earlier post that the unit consumes less than 10W - so I think this 2x25V 30VA would be more than suitable?
https://uk.rs-online.com/web/p/toroidal-transformers/6719084
ETA: I'll be running two boards from a single PSU.
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Evening folks. I'm using VTB9046M input transformers for my build. Earlier in the thread there was some discussion as to whether pin 6 (earth) should be connected to signal ground or chassis ground, but no definitive answer.
Has anyone else who used these transformers reached a conclusion about which works better?
Has anyone else who used these transformers reached a conclusion about which works better?
I believe that I was the one who asked about that. If I recall correctly, the answer was “try the options and see what works best.” I connected mine where all of the signal grounds converge at the PSU 0v, and it worked fine so I never tried any other option. But I think the advice that both are 0v/Ground so you can try both and see if you prefer one result over the other is good.
I always connect internal shields (which are most often just electrostatic windings) to clean ground as you don’t want to capacitively couple noise from dirty ground to the transformer windings, and an outer shield (transformer enclosure) to chassis so any hum and noise captured by the external screen are dumped to the dirty ground.
Hi everyone,
Could someone please tell me if it's the correct orientation for fast/slow and short/long?
As far as i remember, I saw mainly numbers on other people's builds, and i'm not sure i get it right..
Thanks!
EDIT : actually found it for release on post #544 by fripholm : longest time constant = pot fully clockwise
Could someone please tell me if it's the correct orientation for fast/slow and short/long?
As far as i remember, I saw mainly numbers on other people's builds, and i'm not sure i get it right..
Thanks!
EDIT : actually found it for release on post #544 by fripholm : longest time constant = pot fully clockwise
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Hi there, i have another concern, this time related to relays..
I know there has been lots of talks about it on this thread but i'd like to be sure i get those words right... so please someone tell me if i can connect things like in my high quality drawing or if i totally missed something?..
Thanks a lot!!
I know there has been lots of talks about it on this thread but i'd like to be sure i get those words right... so please someone tell me if i can connect things like in my high quality drawing or if i totally missed something?..
Thanks a lot!!
This doesn’t look right for relay bypass. Based on your drawing, I think there are a few things you should think through that will help you make better sense of it.
1. How do the switch and relay actually make their internal connections? It seems like you are visualizing them as a left-right pass-through connection, which they are not. Currently, your connections from Byp1-SW, SW-Relay, and Relay-Byp2 are all isolated from each other (and the SW-Relay connection is completely isolated from anything, including the main circuit). They will never connect as drawn, regardless of how you flip the switch.
2. Similarly, make sure you know which pins on your relay are the poles (the common pins). If you get that wrong, then even a well thought-out routing will fail to function. It’s not always the middle pin. Check the data sheet for the relay you are using, or look at the relay itself, as it is often illustrated on the top of the case.
3. What is the function of the switch and what is the function of the relay? A relay is an electrically controlled switch, so your current layout — even if it worked as is — creates redundancy, and also appears to keep the relay permanently in the energized position. In this application, the relay is meant to switch/direct the signal path, while the mechanical switch is used to deliver/cut off the +28v that induces the relay’s switching action (as well as the LED, see below).
4. Ignoring the concern in #1 above, the LED placement in your drawing is acting like a diode, but it is not going to light up or function as an indicator. You need it to be on a power rail, not in the signal path where it seems you were trying to put it.
I hope this helps. I suggest taking some time to look at the connections and to try to wrap your head around what you are sending where, and why and how you are doing so. While stuffing a pcb may be like paint-by-numbers (as long as it is well-designed), this part is like a little puzzle that you have to figure out. But it will be worth it once you do. Send an updated drawing when you have one and we can continue to give feedback until you get it working like you want.
EDIT: Just for the sake of completeness, you've labeled your mechanical switch DPST but drawn a DPDT. As you work out the correct wiring paths, make sure you know which one you need to order.
1. How do the switch and relay actually make their internal connections? It seems like you are visualizing them as a left-right pass-through connection, which they are not. Currently, your connections from Byp1-SW, SW-Relay, and Relay-Byp2 are all isolated from each other (and the SW-Relay connection is completely isolated from anything, including the main circuit). They will never connect as drawn, regardless of how you flip the switch.
2. Similarly, make sure you know which pins on your relay are the poles (the common pins). If you get that wrong, then even a well thought-out routing will fail to function. It’s not always the middle pin. Check the data sheet for the relay you are using, or look at the relay itself, as it is often illustrated on the top of the case.
3. What is the function of the switch and what is the function of the relay? A relay is an electrically controlled switch, so your current layout — even if it worked as is — creates redundancy, and also appears to keep the relay permanently in the energized position. In this application, the relay is meant to switch/direct the signal path, while the mechanical switch is used to deliver/cut off the +28v that induces the relay’s switching action (as well as the LED, see below).
4. Ignoring the concern in #1 above, the LED placement in your drawing is acting like a diode, but it is not going to light up or function as an indicator. You need it to be on a power rail, not in the signal path where it seems you were trying to put it.
I hope this helps. I suggest taking some time to look at the connections and to try to wrap your head around what you are sending where, and why and how you are doing so. While stuffing a pcb may be like paint-by-numbers (as long as it is well-designed), this part is like a little puzzle that you have to figure out. But it will be worth it once you do. Send an updated drawing when you have one and we can continue to give feedback until you get it working like you want.
EDIT: Just for the sake of completeness, you've labeled your mechanical switch DPST but drawn a DPDT. As you work out the correct wiring paths, make sure you know which one you need to order.
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Hi JMan, thanks for your answer!
I know i was trying to get the easy way, thanks for giving me hints that will -maybe- allow me to find the answer the other way!
-DPST yes, my mistake!
- when i had to use relays they were on a PCB and as you say, it's a monkey game. Here it's real deal and yes, i really don't get how those guys work....
- I was leaded by the drawing in the build guide, and, as they show very similar to the switch, i got a bit lost.... see attached picture, where the 2 poles are in the same position on the switch and on the relay, with the same labels In/Bypass also on both... apparently taking the input signal from the same Pole1/Pin2
-I have no infos on my relay case about the pins, just the small "notch" like on an IC
Will go, with the help of your remarks, investigate a lot more
Thank you!
I know i was trying to get the easy way, thanks for giving me hints that will -maybe- allow me to find the answer the other way!
-DPST yes, my mistake!
- when i had to use relays they were on a PCB and as you say, it's a monkey game. Here it's real deal and yes, i really don't get how those guys work....
- I was leaded by the drawing in the build guide, and, as they show very similar to the switch, i got a bit lost.... see attached picture, where the 2 poles are in the same position on the switch and on the relay, with the same labels In/Bypass also on both... apparently taking the input signal from the same Pole1/Pin2
-I have no infos on my relay case about the pins, just the small "notch" like on an IC
Will go, with the help of your remarks, investigate a lot more
Thank you!
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warpie
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I'm not sure if it's a good idea to feed a 24V relay with 28VDC.
I think that's been standard practice in this build, and no one has reported issues. Of course, it's possible that it may cause the relay to wear faster, thus becoming something of a longevity concern, but I'm not sure. It seems that most nominal 24V relays are sufficiently rated to handle 28V without incident.
I understand. I remember when I was first trying to work out the bypass on this, I also had some confusion.
In that drawing you posted from the build guide, it's showing 2 different methods -- the switch OR the relay -- for directing the audio path. If using the relay method, you'll then need an additional switch (not shown in the drawing) to control the +28v to the relay coil and LED, if using. If you are not using the LED/illuminated switch, then a SPST or SPDT toggle switch will be sufficient. If using the LED, you'll want a DPST or DPDT (note that illuminated switches have a built-in LED and will almost certainly be this latter type).
I mocked up this drawing that I think should help clarify how the different connections are happening. (I did this quickly, so hopefully I didn't make any errors myself). Again, note that you MUST know which pins on your relay and your switch are the Poles/Common, Normally Open, and Normally Closed, and understand how that relates to the bypass pads on the main board and the flow of your DC voltage. Otherwise it will not work as advertised. The arrangement of relay contacts in my drawing is different from the illustration in the guide because it was more convenient as I was drawing. The relay is marked, the other one that I forgot to mark is a mechanical DPDT switch -- as you can see, the Normally Closed pins are unused, so a DPST would be fine here as well.
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Thanks for your drawing JMan, it helped a lot!
Although i'm not 100% sure, i made a new drawing (same quality, sorry!) which includes both channels BYPASS (i ommited BYP1/BYP2 connections on the "right/B" channel for clarity), and also the LINK switch, wich i'd like to also have a LED indicator.
So i guess if this is correct, all 3 switches could be DPST.
About the lower part of my drawing :
If it'd be needed or better for longevity, one could try Ilya's zener voltage drop (i don't know about that) or a simple resistor to go down to +24v (which can simplify the wiring i guess but maybe it's not a good practice?...).
Thanks everyone!
Although i'm not 100% sure, i made a new drawing (same quality, sorry!) which includes both channels BYPASS (i ommited BYP1/BYP2 connections on the "right/B" channel for clarity), and also the LINK switch, wich i'd like to also have a LED indicator.
So i guess if this is correct, all 3 switches could be DPST.
About the lower part of my drawing :
If it'd be needed or better for longevity, one could try Ilya's zener voltage drop (i don't know about that) or a simple resistor to go down to +24v (which can simplify the wiring i guess but maybe it's not a good practice?...).
Thanks everyone!
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This looks pretty good now. (I’m not sure where the suggested Zener should be placed, but I suppose this will work as you’ve drawn it).
Do you already have your relays? Can you share the part number so we can look at the data sheet? That way we can determine which contacts are which.
Do you already have your relays? Can you share the part number so we can look at the data sheet? That way we can determine which contacts are which.
Yes, that sounds about right. Okay, the data sheet doesn’t tell us much, but I’ve used these relays before and this is what I remember:
Pins 1 & 16 - coil
Side “A”
Pin 4 - Pole 1
Pin 6 - NC
Pin 8 - NO
Side “B”
Pin 13 - Pole 2
Pin 11 - NC
Pin 9 - NO
(Just spelling it out because I know the build guide drawing could lead you to assume that pins 6 and 11 are the poles, and if memory serves me, that is not the case).
I stuffed these boards over 4 years ago, then priorities with both life and the studio shifted, and now I’m finally ready and excited to build this. I have everything except the front panel, which I need to modify the design a bit from the one below, as I decided to spend the extra money on the legit Stockli knobs from Don Audio (they’re longer than what I originally designed for) and also not go with the stepped I/O. I made some progress with the components layout tonight. Now time to start reading the build guide and all 40 pages in here again to refresh my memory on this build haha.
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