HV and SDC PCB design

PCB layout
dimensions are in mils [1mil/40=1mm]

Bill of Materials for HVandSDC

Revised: Sunday, June 28, 2009
Revision:
Bill Of Materials June 28,2009 14:13:22
Item	Quantity	Reference	Part	Note
__________________________________________________________________________________________________________________________________
1	2	C1,C7	100n/1000V
2	22	C2,C4,C8,C10,C12,C13,C14,C17,C19,C22,C23,C27,C28,C29,C31,C37,C40,C42,C43,C47,C48,C49	100n	ceram ~40V
3	1	C3	1m/35V	elyt
4	1	C5	10n/1000V
5	1	C6	200n/1000V
6	1	C9	50n	ceram ~40V
7	5	C11,C39,C41,C45,C46	100u/35V	elyt
8	4	C15,C30,C44,C50	100u/16V	elyt
9	6	C16,C21,C24,C25,C26,C36	10u/16V	elyt
10	5	C18,C20,C32,C34,C38	150p
11	1	D4	Zenner 6.2 V
12	1	D6	Zenner 4.7 V
13	5	D1,D2,D3,D5,D8	1N5408
14	1	D7	1N4700
15	1	F1	4A	GME: E-CH10 500V gG 4A
16	1	J1
17	1	J2	Spark Plug
18	1	J3	ARM PLUG
19	1	J4	BATTERIES
20	1	J5
21	1	J6	Digital I/O
22	1	L1	470uH	min 1A, toroid
23	4	L2,L3,L4,L5	10uH	min 0.5A, axial
24	3	R8,R9	10k
25	1	Q1	BC337
26	1	Q2	BC237
27	1	Q3	BC546
28	3	R1,R17,R19	1k
29	1	R2	1meg	HV
30	3	R3,R5,R6	0	see Item 28
31	1	R4	5k
32	1	R7	2.7meg	1000V (serial combination with R3,R5,R6)
33	5	R10,R12,R15,R16,R18	100R
34	1	R11	470R
35	1	R13	4.7k
36	1	R20	400k
37	1	U1A	tl497
38	2	U2,U6	ADuM1100	Order in Analog Devices !!!
39	1	U3	7404
40	1	U4	AD741
41	1	U5	TS555
42	1	U7	LM7805
43	1	U9	LM7808
44	1	Z1	BUP313
45	1	P1	10k	R Trimmer/ Multi-Turn; GME: 64 P 10K (http://www.gme.cz/cz/index.php?product=112-264)

Complete schematic for HV and SDC PCB design

HV Source Final Design

Modified: timming capacitor C10 -> 50nF
feedback values
Added: connectors
digital insulation
filters
safety OFF mechanism
LED indicators

Structure model-testing

Fixing into the Gondola

SOFTWARE LAYOUT

Spark Detection Circuit Update

Added VDD=8V for OA
Added Zener diode 4.7V D3 for OA's LOW output voltage shifting

Project Planning Update

ROBUST shiny metal EXPERIMENT MECHANICAL STRUCTURE

High Voltage Spower Supply Test

input voltage 12 VDC; current drain 250 mA
output voltage 800V
input voltage change +- 2 V => output voltage change +-10V
load 10Mohm => 5V shift
output voltage ripple +-2V

Spark Detection Circiut Test

Upper Trace(CH1): Discharge Voltage
Lower Trace(CH2): Spark Det. Logical Signal

Upper Trace(CH1): Discharge Voltage
Lower Trace(CH2): Spark Det. Logical Signal

Log. signal delay: 1.25us

Medipix@ATLAS

=> Lot of important data foreseen for analyses in synergy with our balloon experiments and potential scientific satellite applications!

http://pcatdwww.cern.ch/local-server/pc-medipix-01/devices/

New Ionisation Measurement Concept

...was proposed.
Measuring few points of V-A Chart before a spike => no EMC interferences.
HV ~ 100V digitally adjustable
- uC unit will have an extra dig. outputs
- HV PS will have an D/A converter in the feedback for adjustment

Current measurement by a TIA (with integration)

Double shielding will be still necessary but now in opposite way.
Electrodes: 100x100 mm

TO DO list:

- JOSHY time schedule and task interest

- funding (Vasa, SSC)

- ion concept discussions - Spanel, Svoboda, UTEF...

- STANDARD radiosonde detailed info from LEBEDEV inst.

industrialPC-uComp interface

pending decision about:

incorporating reset function into uControler having two separate ETH interfaces through E-link, 

OR

using single ETH on indPC, uControler connected to serial to it (indPC) WITH TESTED WATCHDOG function

Project Planning

PDR documents sent out

CRIndIons SED and PDR presentation sent to ESA.

3D model

updated version

ESRANGE provided battery source confirmed

A 28V/1A battery power will be supplied to each experiment if needed. The experiment

must have a 4 Pin connector type MIL – C-26482P series 1, placed on the outside of the

structure / housing.

If the experimenter chooses to use some other electrical system or batteries, it has to be

discussed with the BEXUS project manager before the critical design review (CDR).

Breakdown voltage environmental dependences

From easy calculations based on Paschen's law (i.e. WIKI) 5.7mm is the optimal effective distance of our spark-plug electrodes to obtain best results having available just max 800V potential. 

This graph is for parallel electrodes separated by 2.5cm. Find on figure for air 1 torr=133.3Pa) expected lowest pressure during flight will be ~ 0.1 Torr so well in our range. Max (ground) pressure ~700 Torr so we can effectively operate from on almost whole range with optimal 5.7mm distanceand from ~10km up higher even with 2.5cm distant electrodes.

More interesting, dependences on temperature and humidity as well> http://home.earthlink.net/~jimlux/hv/paschen.htm

Vbreakdown = 24.22 * x + 6.08 * SQRT(x)

 x = 293 * p * d / (760 * T)

p = pressure in Torr (mm Hg), d = distance in cm, T = Temperature in Kelvins, Vbreakdown in kV

Aluminum profiles

http://www.betz.cz/download_soubory/Hlinikove_profily_Bosch_12.pdf
http://www.betz.cz/download/soubory_ke_stazeni.html

3D Model

I just render this image.

Risk Management

analysis was done and sent for comments.

Electrical Design CHapter

was written and distributed for comments.

Update of HV source

Micro Controller

Micro controller unit was designed

Supply: 5V@2mA
40MHz clock ~10MIPS
RS232 interface
Humidity sensor input
1 dig input
2 dig outputs

Complete Spark Detection Circuit

Output TTL pulse duration is ~110 ms

Logo

by Jitka

Spark Detection Circuit

Spark Detection Circuit was designed and simulated
RED trace: Output signal
GREEN trace: Spark plug voltage

Required supply voltage is +5V.

Safety charge is 50uC. It's 50uF @ 1000V => 10nF @ 800 V SAFE ENOUGH

There will be a shaping 555 circuit that wasn't simulated.

Ionisation tube

Concept of Ionisation tube and EMC.

Ionisation tube will be an independent module with double shielding. It will have it's own battery power source and all digital I/Os will be insulateted by the ADuM11001. It is a digital isolator based on Analog Devices iCoupler technology. Combining high speed CMOS and monolithic air core transformer technology, this isolation component provides outstanding performance characteristics superior to alternatives, such as optocoupler devices.
The spark plug will be out of the gondola.

#It's a question, where to place the humidity sensor. It should NOT be inside of the Ion. tube, but it can be mounted on it (outside the double shielding).

5V switching power supplies

we still have 2 PCBs for the 5V/2A PS and and can be used for new power supplies. I suggest to use both of them in parallel for back up.

Thermal scan of the TimePix

The thermal camera cannot be moved from the CTU. We have to move the TimePix to my office. Waiting for approve from the IAP.

New chapter for the SED

abut the thermal design was written and distributed for comments.

Thermal scan

HV Power source

HV source was designed and simulated. HV is ~900V (stabilized and adjustable).

Old Timepix Experiment

moved to my office at CTU. Without Medipix detector.

Spark initialization voltage dependence on initial Ion concentration

We found out that there is obvious dependence of Spark initialization voltage on initial Ion concentration. The detailed feasibility study of the ionization concentration in the range of altitudes requested is ongoing, results to be provided in the range of interest. Concerning the BEXUS7 floating altitude of 27km, the ambient pressure was 19Pa, Resp. BEXUS6 at floating 30km with 10Pa.
Therefore 10Pa is the relevant minimum for our experiment, with start of relevant function of our ionization tube function above 10km of altitude, with ambient pressure of 20kPa. Dependence plots of temperature and pressure coming soon.

Tests

A thermal camera for thermal design at CTU is available. EMC test of the ionization tube has to be prepared.

New log book

New log book was created