Toy13 D/A with tube amplifier

D/A High voltage use R-L-C-L-C net to generate 230V for Tube 6922 plate-voltage.
Rectifier is 6Z4 and put in delay-on function.


D/A output OP +15/-15V power supply by switching power.


Spdif receiver is CS8416 and Codec is WM8741.


All circuit design usage SMT components.
Serial audio path usage DIP components for high Q factor issue.


The view of Audio signal switching and audio-input of tube.


D/A Top view picture.


Add 6922 heater R & C components.



Add Tub output OPT for good sound.

Toy12 Plasma tweeter Diy-7

Prepare close shielding-net I buy a big heat sink from internet.
Heat sink drill holes for mount 120w resistors.


Measure pitch distance.


From rear side to Drill holes to fix heat sink.


Finish heat sink and resistors assembly at rear side.


Rear view.


Top view.
I put on a current meter for monitor high voltage.



Another picture.

Toy12 Plasma tweeter Diy-6

Order 120W VR for step down high voltage.


Put resistors on wood rack and finish high voltage connection.


After long time debug a tiny flaming just pop out.
So far I could make sure my circuit of RF TUB amp. is workable.
But I still need to tuning work voltage and current of PL519 to improve flaming make it large.



Zoom in picture.


Re-modify working voltage and current 480V and 0.2A.
No sound modulation in and Just carry frequency radiation.



Modify flaming size.

Toy12 Plasma tweeter Diy-5

After  check high voltage generate have a problem cause by step-down resistor.
Because PL519 will take 580V/200mA so resistor of step-down is hot .
Step down voltage about 250V by 0.2A ...74W.  Estimate need cascade a 200W resistor for low temp. profile operation.



Finish IF circuit high pass filter and measure modulation out about 105V ...in spec.
But ECL82 and 6C45pi Plate-voltage need check again when replace high voltage resistors.



Because RFC inductor is hard to buy on internet So I  use a 20 ohm resistor hand make a RFC.



Top view.

Hand make Ring wire for PL519 feed back circuit.

Toy12 Plasma tweeter Diy-4

This week finish audio amp. (6C45pi) and IF modulation (ECL82) circuit.


For good shielding reason I design to build a small space for IF module.
But this cause it's hard to hand make and modify circuit.


Finish IF high-voltage and prepare for 6C5pi,ECL82,PL519 heater test.
Meanwhile I measure PL519 (insert already) heater voltage only 36.4V.
I got check spec. of  PL519.  So far the transformer of heater  is one way ticket.



The PL519 heater light is turn on.

Toy12 Plasma tweeter Diy-3

Fix shielding net on front side and assemble power bottom panel.
Mid panel for fix volume knob.


Fix shielding net on rear side and assemble AC connector.
Mid panel for fix Audio in RCA jack.


High voltage Design in a delay on relay (about 10 sec.) for heater turn on first.
High voltage I usage 2 times frequency boost to 1000V then step down to about 600V.
Finish L channel C-R-L-C filter.


Finish R channel high voltage connection.
IF frequency high voltage about 500v than step down to 350V for ECL82 plate and setp down to 190V for 6C45pi plate-voltage.



Two times frequency boost to 1000V Rectifier tub is 5U4G.

Toy12 Plasma tweeter Diy-2

Fix front plate and rear late.


Placement IF components.


Placement high voltage components.


Prepare net of copper.


For radial issue to prepare shielding nets.



Extend shielding nets for each block of plasma tweeter.