| two 10K resistors | 1% metal film, best temperature stability of general commercial price range. Sub wire wound if available. 1/8 watt on all resistors. | Suggest Mouser Electronics for all
resistors, caps and pots. Price hard to beat, and all ranges of types and nice descriptions/layout of catalog. http://www.mouser.com |
| two 10 ohm resistors | " | Radio Shack (RS) has some limited metal film variety of values. Check them for other parts and pieces also. |
| one 620 ohm resistor | " | - |
| one 1K resistor | " | - |
| one 4.7K resistor | " | Or...two 10K paralleled together, check for ~ 4.7K |
| two 100K resistors | " | - |
| one 1M resistor | " | - |
| one 5.1K resistor | " | Or...two 10K paralleled together and check for ~ 5.1K |
| one 20K, 10 turn potentiometer (zero/null) | wire wound preferred for long term wear resistance. Can be most expensive item...check around. | 10 turn trim pot wire wound would probably work OK, but more difficult to rapidly adjust. Alot cheaper. |
| one 20K, 2/3rds turn potentiometer | wire wound preferred | Could sub carbon pot as it probably won't be changed alot compared to zero pot. |
| three 10 to 47 microfarad caps | Tantalum preferred | can try electrolytic (at RS) |
| one, .1 microfarad cap | mylar (non-polarized) | probably any, but check for polarity marks if others used. (RS) |
| one, 1 microfarad cap | mylar (non-polarized) | probably any, but check polarity marks if others used. (RS) |
| one, 100 picofarad cap | any | any ceramic etc. |
| one, 1 to ~ 15 microfarad, nonpolarized cap, on the "period" sought. (Measure the actual capacitance of each capacitor for the real value, other than marked.) | Film or mylar: ~1ufd for each second, i.e., 15 seconds = 15ufd. Suggest obtaining a number as the differences can vary wildly between caps in one same brand, value, infinite resistance. DMM with a capacitance input will show actual values etc. | Important: check on DMM for VERY low leakage, i.e., highest resistance, cap should read infinite resistance after loading time allowance per ?ufd. |
| two, general purpose diodes 1N918, etc. | any general purpose | any (RS packet available) fine.... |
| two LM163-5.0, or LM263-5.0, (TO-46 metal can pkg's, or, possibly the LM363-5.0 (TO-92 plastic pkg), which is cheapest of all. These are 5 volt voltage reference sources. | Must be 5v capable of ~ 10 mA. Digi-key catalog. ~ $1.33
up to ~
$16.00 various metal/plastic models of 163/263/363 varietys. Haven't tried cheap plastic here, but it may work fine? |
Variety on market but, if the design is different, you will have to accomodate per the different brand you get. |
| one, LF411A, or LF412A dual op-amp. Don't use the LF411 or LF412 as the drift is about twice. | LF412A has 1/2 drift of LF412. Only burned out one because power supply went ka-poot. Circuit requires a very high input impedance IC like this. LF411A cheaper. | Digi-Key catalog. See http://www.digikey.com to request free
catalog.
Allied catalog. Prices lower. http://www.allied.avnet.com |
| one, Allegro, linear Hall UGN3503 or the A3515. | choice depends on your seismo. Suggest A3515 for S-G, and UGN3503 for garden gate horizontals with their wider drift span. | (available from RS via special order for around $6 each)
Check for other
sources/prices. Newark has these also. |
| one single pole double throw switch. Your "DC-AC" mode switch | solid contact preferred | Any. R/S |
| one circuit board | General new circuit building type. One could use the plug in variety to test the circuit, but, the contact problem will likely lead to problems in time. | large variety on market (RS cat no. 276-170 suggested as the traces are more separated which means less possible soldering shorts) |
| one dual polarity power supply +-10 to 15volt, or adjustable down to
this. Probably need no more than 100mA,
per circuit. |
two single connected in series or surplus sources, or homebrew from multitude of circuit designs and parts. | large variety of singles on market (could buy two RS 273-1652D, 12vDC at 500mA, and series +-+-, $12.99 each) This supply combo could probably run a big bunch of Hall circuits. |
| one 8 pin IC socket, but maybe two if you want to plug in Hall on your circuit board for tests. Possibly 3 if used to plug in Hall on your seismometer. | Any, but inside gold plate contact probably best over time. Bad contacts can drive one crazy | Sub any (RS) |
| Soldering Iron, and solder | 25 watt, small tip suggestion | Any. If you have never done this before, practice first and strive for shiny solidified joints, not the ragged matteled bad joint stuff. R/S |
| Digital Multiple Meter, strongly recommend one with a capacitance range, and high resistance range of perhaps 200M ohm. | I use the Wavetek 27XT, but only a possible suggestion. No problem 1/2 year of use. Large probes awkward, see if it possible to get smaller clip-ons. | Any suitable DMM. Price ranges run up too and over $100.00 US.
Most important and essentially necessary test instrument. R/S has 2 that
may
fit the description. |
| Misc. insulated wire | any | R/S variety |
| Wire cutter | any | R/S variety, Home Depot etc. |
| Circuit Chassis Box | any that fit, prefer aluminum for its
shielding aspect, and easy to work. |
R/S variety |
| Misc power tools, drill bits | to work chassis | hardware store etc. |
| R/S has resistor packs with different
values, that maybe cheaper than separate value purchases, but most are carbon variety. Ask if not marked as to composition (type). |
Other sources around | Metal film more temperature stable
than carbon resistors. |
Price variations among sources are often great, check a variety for best deal. Some offer fast delivery but the prices are usually significantly more than others. Some only accept credit cards. Mouser Electronics takes about anything, and still has a nice variety with nice descriptions; at a very competitive price, and even has a real mail order form available via site download, (no joke). Some only want web download order, which is OK if you have a credit card and your ISP gives you alot of time before shutting you off...terrible if you want alot of items.....
The components and parts listed here are subject to change over time, due to improvements, or other cost considerations.
This page last update 10/25/98