Circuit Boards and Fixtures

New Activities

  1. QVGA Contol board in the shop
  2. LPF-140 board in the shop
  3. SMD Rework Station
  4. DIY Convection Oven Design
  5. Amp Fixture
  6. PSU Prototype and Design

QVGA Control Board is a prototype 4–layer board for our VGA Display on the Amp Module.

Qvga control crop

This board has the Processor with a built-in LCD Controller. It features a SRAM, Parallel and Serial Flash memories plus 4–wire touch screen control. The board size 4 x 3.5 inch. The LCD glass mounts on the backside of this module and is what is seen from the front panel. This is a very powerful piece of the puzzle that communicates between you the user, the amp module and the outside world. The prototype board for this item is in the shop.

LPF-140 Low Pass Filter Module.

Artwork LPF-140R0

This board is the low-pass filter module that covers 160–10M. It is relay controlled and intended for continuous duty. Note the flat cable interface on the right end of the board. Input and Output utilize the SMA style connection cables.

SMD Rework Station

SMD Rework Station

This piece of assembly equipment is need for SMD circuit board assembly and rework. It shoots out an adjustable hot air stream to solder or unsolder components on a circuit board.

DIY Convection Oven Design

DIY Convection Oven

The convection Oven is a design in process. It consists of a hot plate (Aroma) with a 6x6x1 inch block. A thermocouple is embedded from the rear of the block. The missing piece (in design) is an aluminum cap (6x6x3) with a glass viewing window that will sit on top. This off-the-shelf utility box will be used. I will put little bar strips as needed to hold the cover in place. The PID Controller gives me the programming ability to automate the sequence of soldering SMD circuit boards. I can program a timed ramp followed by a soak time to equilibrate and then a Reflow cycle followed by a cool down cycle. An external fan will be used to quickly get the temperature back below the reflow state. When you are on a budget, a few purchases from Ebay can save you thousands for a commercial unit. The goal is to be able to assemble and test the modules in-house and save a lot of expensive external labor costs. I want to have a piece of equipment that will consistently solder in the same way to control the quality of the work.

I am on the lookout for a stereo microscope that I can use to place the SMD parts. It would be helpful to have an X-Y table and a vacuum chip holder to aid in chip placement. If you know of where something like this can be cheaply obtained, it would help the project.

Amp Fixture.

Test fixture amp

This is probably a repeat picture. The progress made here is the arrival of the SMD cables and the thermal plate material used between the amp circuit board and the heat sink mounted on the skin of the case. The open space is where the LPF-140 Module will mount along with the PSU Module.

PSU Prototype and Design


This is the top view of the 48V, 5A PSU. We will be using this purchased demo board for the first prototype and creating our own reproduction possibly using a Quad-Phase design that will have 8A capability about the same size. This design is very high efficiency that does not even need a heat sink.


This is the bottom view. Note the Inductors and capacitors.

Finally, thank all of you who have stepped up with $200 deposits for the project. All those deposits are greatly appreciated and put to good use to move the project along. The way it works is that the money is applied as R&D Expense with a discount credit to the builder for the amount deposited.

All the best for a happy new year! Until next time..

73 K5OOR –  Virgil




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