Ion Source and Faraday Cup Biasing Power Supply (dual 0-350v and 0-4000v)

I made this dual high voltage power supply for an ion source (0-4kv) and also to bias the collector in a Faraday cup to remove secondary electrons from measurement (0-350v, typically 90v). There are 2 boost converters for the high voltage and one buck converter to power the 0-4kv boost, which is an Emco F40. It can provide 4kv @ 2ma and is connected to the MHV connector on the back panel. The Faraday Cup bias supply outputs through the BNC, and the main power connector is a 12v in through the barrel jack. There is a 10 turn potentiometer on the front panel with locking knob for precise adjustment of the high voltage.

IMG_0124 IMG_0125


Spellman High Voltage Reference Manual

6mhz TTL Oscillator Used as Quartz Microbalance


A 6mhz oscillator can was cut up with pliers and the top was removed to expose the quartz crystal. The output is AC coupled (high pass filtered) to the positive (+5v) rail so that a single coax cable can be used to connect this to the thickness monitor as the power is basically just a DC offset on the signal. If you buy a pack of crystals from somewhere like Lesker they will (depending on your thickness monitor) most likely require the usage of an external oscillator. Such a circuit can be made by a complimentary pair or NPN and PNP transistors and couple passive components. Thanks to Ben from Applied Science for the idea.

Abstract: The quartz microbalance is a quick way of monitoring thin film thicknesses in real time, a bare quartz crystal which oscillates at a known frequency is placed in the chamber near the substrate involved in deposition. As the film accumulates on the crystal, it gains mass and the resonant frequency is lowered. The cumulative frequency change is analyzed and interpreted as the rate of accumulation the rate is integrated into a total thickness. Note that accumulation rate is the proper term for deposition rate, as in many cases (sputtering) the actual deposition rate is higher but some atoms are resputtered off the substrate due to high energy molecules in the chamber, substrate temperature, etc. and the total film thickness can momentarily decrease. The net result of the deposition and resputtering is known as accumulation


+/- 0.1nm resolution!

Switch Mode Power Supply Design + laser cut/etched PCB

IMG_7582 IMG_7560 IMG_7559 IMG_7321 IMG_7319

Buck/Boost converter design for a solar glider I was working on last summer, at 16v it reached 98% peak efficiency and 95% average in boost mode. Also tried to make a linear power supply board using a laser engraver to cut away the copper, it worked pretty well to replace the normal ferric chloride etch step. Continue reading Switch Mode Power Supply Design + laser cut/etched PCB

DIY Doppler Radar – LNB Hack

I modified a satellite LNB to transmit as well as receive on 10ghz and connected the downconverted signal to my scope. I can use it to measure doppler shift and therefore speed of a moving object. I did the modifications by removing HEMT RF FETs and rotating them so their gate is where their drain was and vice versa. The source connections stayed grounded. I then had to cut some of the traces on the board and change a few resistors and things to make the biasing circuity work in reverse. I then capacitively coupled the dielectric resonant local oscillator the the transmitting section that I made. Watch Jeri Ellsworth’s Videos:

A similar mod can be done to use these as 10ghz ham radio transmitters:

Mod closeup pic:


DIY Arduino Variable Lab Bench Power Supply 0-30v CC/CV

DIY Arduino lab bench power supply 0-30v 0-3a cv cc

This power supply can be built for less than $25 sans enclosure



Parts List: (see schematic)
Assorted resistors and capacitors (see schematic)
Optional: (see schematic)

Cool enclosure
Potentiometer knobs
Binding post output
Big heatsink for transistors