KGSSHV Carbon Build Thread

[mwl168]

I took the AC filament directly off the windings of the Antek transformers for the BH and GG. 

And yes, B+, B-, bias and +/- 15V for the JFET front end (I use +/- 18V) are all you need for Carbon. Add filament supply for GG and BH. Plus supply for the HV delay if you decide to implement it (I recommend you do).

 

 

Edited June 13, 2019 by mwl168

[JoaMat]

13 hours ago, mwl168 said:

I need to correct myself. The above statement should be "Both boards have the built-in HV soft-start circuit...". 

The soft-start circuit is intended for HV delay but the "delay" part needs to be implemented separately off board. There are many such delay modules available on eBay or you can simply wire a manual switch like I did. 

 

13 hours ago, jose said:

I use an arduino controlling an SS relay on the primary  of HV transformer. You can also use a circuit similar to T2 (with a LM555). It's very easy to do.

or 4093 - used by Stax, Kerry and myself.

[Hirsch2k]

Transformer and wires finally arrived. Unfortunately I have two +400V GND BIAS PCBs and no 15V -400V PCBs ?

If anyone has a spare +15V -15V -400V "landscape" board I would be happy for a PM.

Additionally I give away a +400V BIAS PCB.

Thanks a lot!

Edit: I got an 8 Dollar coupon at JLPCB so I thougth paying 8,50 dollar for 5 PCBs is probably worth it. 

So I will give away 4 of the +-15V -400V PCBs for cost of shipping. I am located in Germany.

 

[Helium]

If you are making a separate +15/-15VDC power supply board (GRLV), you can do with two Bias GRHV PCBs.

[Hirsch2k]

On 6/12/2019 at 10:21 PM, Pars said:

Thanks guys!

And does anyone have an actual full schematic for these?

Hi Pars,

the pictures you posted look like the following:

Full credit goes to Kevin of course

kgsshvpssicfetsinglenewleftfatsws.zip

kgsshvpssicfetsinglenewrightfatsws.zip

I am building the PSU at the moment. Is the marked 600R for the soft start circuit?

As I understand it, the soft start is mainly important for tube designs and there is no need to populate 600R as well as the CPC1117N in solid state designs?

 

Thanks

[mwl168]

The 600R and the CPC1117N on the back of the board are for the soft start. Don't populate these two parts if you don't need the soft start.

[Hirsch2k]

20 hours ago, mwl168 said:

The 600R and the CPC1117N on the back of the board are for the soft start. Don't populate these two parts if you don't need the soft start.

Thanks, I guess I´ll try without, or it there a good reason to have soft start in the Carbon?

[mwl168]

A few things to consider.

I don't use soft start with Carbon and my other solid state electrostatic amps but I use a thermistor in the primary winding of the PSU transformer to damp the inrush current at power on which provides somewhat of a soft start in my mind.

You also need a DC source and a timer circuit (optional) to implement the soft start which adds some complexity as well. 

[kevin gilmore]

its not a soft start. its a delayed high voltage turn on.  For tubes that don't like voltage before the filament.

no reason to use it except for tube or tube hybrid

[mwl168]

I stand corrected - the primary purpose of the CPC1117N circuit in the GRHV is to provide delayed HV supply to the vacuum tubes. A timer circuit is needed for the "delay" part.

Kevin and/or others please correct me if I am wrong - but I think the CPC1117N itself does provide both soft start and off switching?   

[kevin gilmore]

Yes the opto just provides the on/off switch

you need to use a timer circuit, or a seperate switch and a rolex

 

[Hirsch2k]

18 hours ago, mwl168 said:

A few things to consider.

I don't use soft start with Carbon and my other solid state electrostatic amps but I use a thermistor in the primary winding of the PSU transformer to damp the inrush current at power on which provides somewhat of a soft start in my mind.

Good point, the inrush current with those caps is probably substantial

10 hours ago, kevin gilmore said:

or a seperate switch and a rolex

?

Ok, no delay it is. Thanks a lot!

[steefdebruijn]

I use this one, fed from the 12v lv to delay hv output. https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.nl%2Fulk%2Fitm%2F122078937183

 

I use a drop resistor to feed the cpc1117n

[Hirsch2k]

I am sourcing the LSK389 and there are 4 versions A-D differing in saturation region (see below) and I am wondering which is best suited.

[mwl168]

The LSK389B for the Carbon - it's equivalent of the 2SK170 BL grade.

[hyperma]

Replaced STTH512 by infineon IDH10S120 on PSU ..... Hmmmm.....no output voltage.

I'v chosen this diode for making a "more carbon version KG Carbon", and the performance of IDH10s120 way better than STTH512 on paper but donno what happened.

On 8/8/2019 at 9:12 PM, mwl168 said:

The LSK389B for the Carbon - it's equivalent of the 2SK170 BL grade.

I bought some SMT version of 2SK389 for better thermal coupling and way cheaper......hope it works.

[Pars]

Regarding the diodes, the pinout is the same... seems like it should be superior to the STTH512 and work?

I didn't think the Toshiba 2SK389BL was available in SMT? Only thru hole. The Linear Systems replacement K389 is available as an SOIC8, but aren't marked like that. Where did you get these?

[hyperma]

1 hour ago, Pars said:

Regarding the diodes, the pinout is the same... seems like it should be superior to the STTH512 and work?

I didn't think the Toshiba 2SK389BL was available in SMT? Only thru hole. The Linear Systems replacement K389 is available as an SOIC8, but aren't marked like that. Where did you get these?

 I will replace all bridge diodes by stth512s on Monday, just noticed something.

I bought smt k389 from taobao , they are made by linear.sys , cost 45rmb or 5 pounds , mint choice.

[kevin gilmore]

With those diodes is there any unregulated voltage on the first big cap?

[hyperma]

27 minutes ago, kevin gilmore said:

With those diodes is there any unregulated voltage on the first big cap?

the rms volt of transformer is 348v ,  I cant reach the cap due to parallel installed pcb ,measured 450v from 10m90s and c2ms  drain by multimeter. On monday I will bring oscilloscope to studio.

[kevin gilmore]

Not the diodes

[hyperma]

5 hours ago, kevin gilmore said:

Not the diodes

162v and on heatsink I remember.

[Hirsch2k]

On 8/10/2019 at 6:37 PM, hyperma said:

Replaced STTH512 by infineon IDH10S120 on PSU ..... Hmmmm.....no output voltage.

I'v chosen this diode for making a "more carbon version KG Carbon", and the performance of IDH10s120 way better than STTH512 on paper but donno what happened.

I bought some SMT version of 2SK389 for better thermal coupling and way cheaper......hope it works.

Those solder joints need a bit more love ;)

[hyperma]

10 hours ago, Hirsch2k said:

Those solder joints need a bit more love

Really hate lead-free......unfortunately that's all I got, can't wait to show another PCB I have done with 63/37. 

[Hirsch2k]

On 8/12/2019 at 5:42 AM, hyperma said:

Really hate lead-free......

Ok that is understadable... The fat C2M, Caps and Heatsinks are probably not very enjoyable with lead-free. 

I am collecting more components for my second mouser order and thinking about the on/off switch on the front. What do you think, is it critical or will transients and spikes be completely filtered in the PSU and one can workwith an ordinary push button switch?

I thought about ordering the Amb epsilon 24 with transformer but that will set me back  ~40 dollars in shipping alone ?