Barry Porter "Net EQ"

[druu]

I'm trying to decide to either use 3PDT toggle for switching bands in/out plus LED indicator or should I use a relay based solution? Any suggestion here?

 

[Harpo]

Andrew, 3P toggle for stereo bands+LED, 2P toggle per mono band+LED. Single throw is sufficient but DT is probably easier to source. A relay based solution at least needs a SPST switch+1 or 2 pole relay+flyback diode. For lesser stressing switch contacts from inrush current maybe use the relay activating transistor circuit as shown in Barrys HF-shelf/peak or LF-shelf/peak bands, HP-filter or EQ bypass circuit. An On-Off-On toggle could switch between different min/max amplitude settings (+/-5dB or +/-10dB or whattheheckelsedB) with band bypass in the toggles center position.

 

[druu]

Thanks Harpo! I forgot to mention this will be for a stereo control unit so I'll try source a 3PST first if I can. The relay based solution definitely seems more elegant but I'll try for simple first. Thanks!

 

[Gustav]

Id like to try doing these switches stepped, but Harpo's great work is confusing me. I only see one value going over the switch on each function in the calculator, but several values and multiple decks used on the actual builds. What am I not understanding? Could someone help me get started?

I have a bunch of these https://pcbgrinder.com/image/cache/data/Switches/2x23-500x500.gif
And these https://pcbgrinder.com/image/cache/data/Switches/4x23-500x500.gif


Gustav

 

[Harpo]

Gustav, you've seen post#118 from this thread?
Your question is probably related to frequency selection. Parts values are for each deck, IE 2 decks for each bandpass filters per chanel needed to substitute the stereo pots such as P12a and P12b, 4 decks for single knob stereo operation. For the optional shelfing bands, shelf values (differing from peaking) in separate section for the 3-deck (or 6-deck for stereo) pots 'c' deck.
Column 'F' calculates the resistive value needed with corresponding cap value in column 'E' for wanted center frequency in column 'D'. Column 'J' shows the switched adding up series string of resistors to get close to this target value, IE for switch step 20 in the 2kHz...20kHz section (14.8kHz), the 1K580 value needed is the series string of 1K18+113R+137R+150R.

 

[Gustav]

Gustav, you've seen post#118 from this thread?
Your question is probably related to frequency selection. Parts values are for each deck, IE 2 decks for each bandpass filters per chanel needed to substitute the stereo pots such as P12a and P12b, 4 decks for single knob stereo operation. For the optional shelfing bands, shelf values (differing from peaking) in separate section for the 3-deck (or 6-deck for stereo) pots 'c' deck.
Column 'F' calculates the resistive value needed with corresponding cap value in column 'E' for wanted center frequency in column 'D'. Column 'J' shows the switched adding up series string of resistors to get close to this target value, IE for switch step 20 in the 2kHz...20kHz section (14.8kHz), the 1K580 value needed is the series string of 1K18+113R+137R+150R.

I think/hope part of my brain-short was not realizing, that for a dual pot with identical resistance paths on both tracks, the resistors on the switch should, of course, be identical too, which means they are only shown once in the table.

No replacement for trying, which I will do.

Thanks!

Gustav

 

[druu]

Gustav, just to note that the switches you posted are 23 step but Harpo's spreadsheets are based on 24 step switches. You'll need to adjust the tables to suit if you're using 23 step (I reduced mine to 21 step quite easily).

 

[Gustav]

Gustav, just to note that the switches you posted are 23 step but Harpo's spreadsheets are based on 24 step switches. You'll need to adjust the tables to suit if you're using 23 step (I reduced mine to 21 step quite easily).

Thanks for the heads up. I did notice, and I was actually planning to blow off a step and labeling the unit "2K2 - 20K" and so on accordingly, and depending on which step I left out

If its not rocket science, Ill give the recalculation a shot leaning on Harpo's sheet.



Gustav

 

[druu]

No problem. It's as easy as changing "...(24-1)..." to "...(21-1)..." in the original formula. Hope that makes sense!

 

[druu]

Andrew, 3P toggle for stereo bands+LED, 2P toggle per mono band+LED. Single throw is sufficient but DT is probably easier to source. A relay based solution at least needs a SPST switch+1 or 2 pole relay+flyback diode. For lesser stressing switch contacts from inrush current maybe use the relay activating transistor circuit as shown in Barrys HF-shelf/peak or LF-shelf/peak bands, HP-filter or EQ bypass circuit. An On-Off-On toggle could switch between different min/max amplitude settings (+/-5dB or +/-10dB or whattheheckelsedB) with band bypass in the toggles center position.

Update: I think I may go for the relay based solution. I've just realised I'm having the first steps of the High and Low bands to be 'Shelf' switches with an LED indicator so I kinda forced to use relays.

Harpo, i have a bunch of these sitting in my spares, can I simply use these in conjunction with 1N4148 protection diodes across the coil? I was hoping to put seven of them on some proto board for switching functions. Thanks in advance.

 

[Harpo]

No idea what your 'the first steps of the High and Low bands to be 'Shelf' switches' might relate to.
You are aware, your Axicom relays have a different pinout and different pin spacing than the NetEQ pcb calls for ?
Additional 7 relays * 12V/1028R coil resistance + 7 LEDs with maybe 1K current limiting resistor each = about additional 150 mA load. Better attach a heatsink to your onboard 7812 voltage regulator if this Vreg should supply this additional load. Relays default setting probably set for band engaged and LED indicating band bypass with relays coil powered. YMMV.

 

[druu]

To elaborate, my Q rotary switches I will have the first step position as Shelf selection, hope that makes more sense.

I was hoping to have the relay default position set for band disengaged as I have the LED as an enabling indicator on my front panel. Will that be an issue? I can install a heatsink on the 7812 no problem, or I may opt to only use the relay solution for the shelving selection and use 3PDT toggles for the band selection. Thoughts here?

BTW, yes I'm aware the relays linked are different. I have already populated the netEQ boards as per the BOM, the additional relays will be on a separate pcb. Thanks again for the 101

 

[Harpo]

To elaborate, my Q rotary switches I will have the first step position as Shelf selection, hope that makes more sense.

Your 'first steps' plural wording was the confusing part.

I was hoping to have the relay default position set for band disengaged as I have the LED as an enabling indicator on my front panel. Will that be an issue?

From Omron datasheet:
>>>Long term continuously On contacts
Using the relay in a circuit where the relay will be ON continuously for long periods (without switching) can lead to unstable contacts because the heat generated by the coil itself will affect the insulation, causing a film to develop on the contact surfaces. Be sure to use a fail-safe circuit design that provides protection against contact failure or coil burnout.<<<
Do whatever you like best, but know your enemy ('long period' is a relative term and when you know the absolute duration of 'long period' you have it exceeded).

I can install a heatsink on the 7812 no problem, or I may opt to only use the relay solution for the shelving selection and use 3PDT toggles for the band selection.

Other than sourcing/fitting 3PDT toggles instead of SPST toggles with remote relays I can see no real advantage of relays here. The peak/shelf relays are already on board.

 

[druu]

Thanks Harpo, I guess I figured the LED indication would be a nice touch but you do have a point.

I'll keep it simple and go ahead and remove the LED indication for the Shelf selection from my front panel design which will simplify things and just use the 3PDT switches I've sourced. Cheers!

 

[Harpo]

I'll keep it simple and go ahead and remove the LED indication for the Shelf selection from my front panel design which will simplify things and just use the 3PDT switches I've sourced.

So pole and pin1 of the 3rd deck of your LF and HF Q switch connect to S2 and S3 and LED2 and LED3 show up for the shelf status. When you already have sourced the 3PDT switches for band bypass, just use the 3rd pole for LED status gimmicks (bicolour red/green LEDs might be to your taste).

 

[druu]

Ahh of course! I had completely forgotten about the provision for LED's already on board. 

 

[Gustav]

Does anyone have a layout for the front panel? (separate controls)

Gustav

 

[druu]

You're welcome to modify the Igortec dual mono front panel I made, to suit.

http://amnet.net.au/~amunday/sontec/

 

[weiss]

You're welcome to modify the Igortec dual mono front panel I made, to suit.

http://amnet.net.au/~amunday/sontec/

hey where did you get these silver knobs from?

 

[Gustav]

I went with some more spacious and "simple". Don't wanna try to take on the entire universe at my first attempt trying to build something like this. 

Still needs a little work, but almost there.

Gustav