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Breaktru Forum  |  eCigarette Forum  |  Modding  |  Topic: Tact switch and mosfet transistor questions
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Author Topic: Tact switch and mosfet transistor questions  (Read 137965 times)

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Online Breaktru

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Re: Tact switch and mosfet transistor questions
« Reply #200 on: November 26, 2014, 12:57:56 PM »
I would call the TP4056 a Battery Charger Controller IC rather than a Mosfet.
I think you should start a new topic for it.
« Last Edit: November 26, 2014, 01:08:23 PM by Breaktru »

Offline davidegee

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Re: Tact switch and mosfet transistor questions
« Reply #201 on: December 19, 2014, 03:48:19 PM »
Hi all,

Mast (a modder from Plumes of Hazard) is releasing a mosfet box that has a 5 click on/off function, which is something i've not seen before and think is pretty cool.

I was wondering if anyone had any idea how to achieve this?

Cheers

Offline mamu

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Re: Tact switch and mosfet transistor questions
« Reply #202 on: December 19, 2014, 04:01:01 PM »
I believe some modders are using the ego board from FT for that 5x click on/off function.

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #203 on: February 04, 2015, 10:13:31 PM »
http://www.mouser.com/ProductDetail/Vishay-Semiconductors/SUP75P03-07-E3/?qs=sGAEpiMZZMtp5ziQ9mm%252bAr%252bCSjsN5ZoY
http://www.mouser.com/ProductDetail/International-Rectifier/IRF4905PBF/?qs=sGAEpiMZZMvsw8vHdI9Fup5iKG09kH7G
I have two mods that will be really difficult to use n-channel. Can either of these be used? I need to use this type if possible. I could parallel two if need be

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #204 on: February 04, 2015, 10:59:31 PM »
I believe some modders are using the ego board from FT for that 5x click on/off function.

Wow I did not see this post Mamu I was happy cause came into mind virginally because a question on ecf about having a puff meter,   using those boards lol  NICE..  Dangit made like 4 orders from ft since Dec lol .... 

I even clicked in here looking for davids post on the charge pump firing the fet didn't even see it  scared:..

It is really cool...

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #205 on: February 05, 2015, 04:43:14 AM »
I have two mods that will be really difficult to use n-channel. Can either of these be used? I need to use this type if possible. I could parallel two if need be

The Vishay part has lower on-state resistance so that would be a better part to use.  However, the threshold voltage on either part would be too high for a single cell.  Would work well with series cells though.  If you plan to run high outputs upwards of 50W then you might want to parallel a couple of MOSFETs, otherwise it should not be necessary.

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #206 on: February 05, 2015, 06:09:26 PM »
I didn't even see the 4.5v.
Why do some have neg numbers such as this one? http://www.mouser.com/ProductDetail/IXYS/IXTP44P15T/?qs=sGAEpiMZZMshyDBzk1%2fWi2Lis36WbXR%252bdOL7vJS80To%3d 
I am truly trying to learn what to look for.


Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #208 on: February 06, 2015, 11:58:59 AM »
Why do some have neg numbers such as this one?

It's just nomenclature.  The N-channel parts are considered to be positive current flow from drain to source.  Since current flows source to drain in a P-channel, it's negative.  Also, gate voltage minus source voltage is positive to turn on an N-channel.  Gate voltage minus source voltage is negative to turn on a P-channel.  Sometimes you see the minus sign in the specs and sometimes it's taken for granted and left out.

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #209 on: February 15, 2015, 11:14:56 AM »
So I gave up and just went with the trusty 3034. How could you incorporate a on/off switch to shut off power so it wont fire? Where could it be placed so that it doesn't get the current flow from the batteries? Its a simple duel 26650 box with a 3034 n-channel but it will be driven hard

Offline mamu

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Re: Tact switch and mosfet transistor questions
« Reply #210 on: February 15, 2015, 01:03:39 PM »
The Gate of the N-FET  is low current, so put the master switch in line with the Gate.  It won't disconnect power but will prevent the atty from firing.

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #211 on: February 15, 2015, 01:51:52 PM »
So I gave up and just went with the trusty 3034. How could you incorporate a on/off switch to shut off power so it wont fire? Where could it be placed so that it doesn't get the current flow from the batteries? Its a simple duel 26650 box with a 3034 n-channel but it will be driven hard

dc99 awesome! look forward to seeing the box!  :beer-toast:  :thumbsup: :wave:

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #212 on: February 15, 2015, 02:53:11 PM »
Thanks Mamu. Its really more of a "I don't want it to accidentally fire thing" so that should work fine. Its was either that or use another mosfet along with the switch. 

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #213 on: February 17, 2015, 12:24:49 AM »
Triple parallel mosfets and gate driver. Anyone have any thoughts on this? Is there is simple minimal component solution for low voltage cutoff (~3v) that could be added?



Minus the charge pump, I made this pcb layout last night in Diptrace. First time using pcb software... I'm sure the design is far from perfect. I was planning on laying solder on top of the high current traces.



« Last Edit: February 17, 2015, 02:13:44 AM by david4500 »

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #214 on: February 17, 2015, 08:26:37 AM »
With gate driver

« Last Edit: February 17, 2015, 07:19:41 PM by david4500 »

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Re: Tact switch and mosfet transistor questions
« Reply #215 on: February 17, 2015, 09:13:45 AM »
Nice pcb
Cannot  beat adding in an ego board it will eliminate your on/off sw and give ya shutdown...
Already know they are highly efficient and will keep at ~4.2v until 3.5ish maybe longer since minimal load..
Only a buck too lol..  Put some pins on it place it one ur pcb easy cheesy..
IMO best thing since sliced bread for our mods..
http://www.fasttech.com/product/2137901


Check out discussions and that 1A charge board I really want one of those

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #216 on: February 17, 2015, 11:27:07 AM »
Nice pcb
Cannot  beat adding in an ego board it will eliminate your on/off sw and give ya shutdown...
Already know they are highly efficient and will keep at ~4.2v until 3.5ish maybe longer since minimal load..
Only a buck too lol..  Put some pins on it place it one ur pcb easy cheesy..
IMO best thing since sliced bread for our mods..
http://www.fasttech.com/product/2137901


Check out discussions and that 1A charge board I really want one of those

http://cnmmtech.en.made-in-china.com/
Heres a place you can get them. Look around, there are quite a few you only have to get 20. A friend on another site ordered a 100 of the 1000ma charging boards

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #217 on: February 17, 2015, 11:53:30 AM »
Thanks DC was being cheap
order 5 testers
waiting for fasttech free shipping and no translating ish
Wonder how warm they get @1A
I found ego boards for 8-15 cents from a manufacturer
I dug deep

http://translate.google.com/translate?hl=en&sl=zh-CN&u=http://product.dzsc.com/product/infomation/997260/201311201466546.html&prev=search


 :laughing:
 :thumbsup:



Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #218 on: February 18, 2015, 02:56:49 PM »
Is there is simple minimal component solution for low voltage cutoff (~3v) that could be added?

Easiest thing to do is add a voltage detector inline with the gate signal.  Take a look at the TPS3700; http://www.ti.com/product/TPS3700

Quote
I was planning on laying solder on top of the high current traces.

Solder actually has about a tenth the conductivity of copper.  It's fine for joints where there's only a thin layer of solder between copper connections but not so great for beefing up current paths.  It's better to add solder mask over the trace then solder a solid copper wire along the length of it.

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #219 on: February 18, 2015, 05:20:01 PM »
Thanks for the help. Much appreciated.

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #220 on: February 25, 2015, 07:30:57 AM »
I'm looking at the MAX8212 since the schematic seems quite simple.

http://www.maximintegrated.com/en/products/power/supervisors-voltage-monitors-sequencers/MAX8212.html

http://datasheets.maximintegrated.com/en/ds/MAX8211-MAX8212.pdf

I would like to wire it as shown in figure 5, vin from the ADM660 voltage doubler and resistors selected for over voltage detection of 6v. (R1=1Mohm, R2=4.22Mohm)

Would the output from the ADM660 be noisy? Should I select and use an R3 resistor for hysteresis with the MAX8212?

« Last Edit: February 25, 2015, 08:11:02 AM by david4500 »

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Re: Tact switch and mosfet transistor questions
« Reply #221 on: February 25, 2015, 07:38:52 PM »
The loading on the detector from the MOSFET gate array is highly capacitive.  Loads that are capacitive result in large current spikes until terminal voltage is achieved.  The detector is not designed to drive loads like that as it has a maximal current loading of 7mA.  Also the output impedance of the detector is rather high so it can result in large on-off transition times for the MOSFET array.  MOSFETs can generate a lot of heat if they switch too slowly.  Based on your use of an array, that's something you're trying to minimize.

What you could do is use a complimentary MOSFET pair to isolate the detector from the load.  Small power MOSFETs in a SOT23 package are a dime a dozen and fairly easy to work with.  Alternately you can use a MOSFET driver.  They can be found with built-in doublers and high impedance control inputs that would eliminate these issues in using a stand-alone doubler.

Your R1 and R2 values are quite high.  Most modern chips have very high impedance inputs so it's not an issue to go with inline resistance as high as a meg, but 5meg is pushing it.  Also it makes things highly susceptible to noise and there will be a good amount from the doubler.  I would suggest a total inline resistance no greater than a meg.  I would take those resistance values down a decade (divide by 10).

I would suggest a 1uF MLCC cap as close as possible to the power and ground pins for both the doubler and detector.  Most chips are sensitive to supply voltage quality and the caps filter some of the noise.

Your schematic shows 10uF electrolytics on the oscillator and output caps for the doubler.  MLCC caps actually do a better job as they have the lowest ESR.  A 4.7uF MLCC cap will offer better performance than a 10uF electrolytic cap and will occupy much less space.  They can be found in leaded packages if you are planning on free wiring your circuit.

I would actually do what you're trying to do quite differently.  I would put the detector right off the battery controlling a MOSFET driver.  Ideally you want the detector right off the battery.  Doublers typically have a lot of output ripple and as you are sensing voltage after the doubler, you can run into issues with false detection due to ripple voltage.  I'd also filter the detection input some amount to provide some noise immunity.  The trigger switch I would put in series with the detector control output.  That's assuming positive logic (active low or low for battery below threshold).  I would use the TPS3700 which provides both and wire the active low output. 
« Last Edit: February 25, 2015, 08:29:44 PM by CraigHB »

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #222 on: February 28, 2015, 01:39:43 AM »
3 smd mosfets, resistor and fuses. Connections for gate disconnect on-off switch, fire switch, voltmeter, 510 and batteries.

https://oshpark.com/shared_projects/TbLFzpbz











« Last Edit: February 28, 2015, 03:05:56 PM by david4500 »

Online Breaktru

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Re: Tact switch and mosfet transistor questions
« Reply #223 on: February 28, 2015, 07:15:09 AM »
Nice work David. Congrats  :beer-toast:

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #224 on: February 28, 2015, 09:15:58 AM »
Very nice work David.

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Re: Tact switch and mosfet transistor questions
« Reply #225 on: February 28, 2015, 11:49:46 AM »
What wattage are ya testing @.   Definitely awesome..  :thumbsup:

Offline wa9w00d

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Re: Tact switch and mosfet transistor questions
« Reply #226 on: February 28, 2015, 12:26:20 PM »
Yes, very neat David.
Have you measured it's voltage drop?

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #227 on: February 28, 2015, 03:02:28 PM »
Thanks.

Coil is 0.2 ohms. Batteries were close to full charge. Battery sag and voltage drop was around .45-.6 volts. My excessively long wires and not soldering the wires to the battery contacts accounted for some of that I would imagine.

Did a 3rd test fire video with a 0.16 ohm coil. Melted the insulator on a TOBH clone... oops... but the board stayed pretty cool.
« Last Edit: February 28, 2015, 03:08:28 PM by david4500 »

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #228 on: February 28, 2015, 04:07:15 PM »
Very Cool! Can you make me one?  :beer-toast:

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #229 on: February 28, 2015, 04:37:05 PM »
Very Cool! Can you make me one?  :beer-toast:

He says as many as you like lol
https://oshpark.com/shared_projects/TbLFzpbz

Thanks David

What fet are you using?  I tried typing in the numbers on em but no luck..
Duh'  found it,  very thorough helps us there lol

https://uk.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=20a3a44206

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #230 on: March 01, 2015, 11:26:41 AM »
He says as many as you like lol
https://oshpark.com/shared_projects/TbLFzpbz

Thanks David

What fet are you using?  I tried typing in the numbers on em but no luck..
Duh'  found it,  very thorough helps us there lol

https://uk.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=20a3a44206

So he owns OSH or just rents there?  :popcorn:

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #231 on: March 01, 2015, 12:31:10 PM »
So he owns OSH or just rents there?  :popcorn:

That would be sweet if he did own it maybe IDK.  Hook us up Davids I see lots of projexts  ;hubba;

No you can buy 3 for $4.80;  or you were serious asking for a freebie?  if so,  me too,  send me one too.   :thumbsup:

I didn't know if you did not see you can buy it at bottom of page,  internet post seems as if ya didn't see that..

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #232 on: March 01, 2015, 12:37:27 PM »
That would be sweet if he did own it maybe IDK.  Hook us up Davids I see lots of projexts  ;hubba;

No you can buy 3 for $4.80;  or you were serious asking for a freebie?  if so,  me too,  send me one too.   :thumbsup:

I didn't know if you did not see you can buy it at bottom of page,  internet post seems as if ya didn't see that..

Not asking for freebies unless he wants to give me one to test or something. I am not seeing where to buy them. Can you link that for me please?   cant_believe:

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #233 on: March 01, 2015, 12:41:58 PM »
That would be sweet if he did own it maybe IDK.  Hook us up Davids I see lots of projexts  ;hubba;

No you can buy 3 for $4.80;  or you were serious asking for a freebie?  if so,  me too,  send me one too.   :thumbsup:

I didn't know if you did not see you can buy it at bottom of page,  internet post seems as if ya didn't see that..

why is this thing double posting sheet?  fainting:

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Re: Tact switch and mosfet transistor questions
« Reply #234 on: March 01, 2015, 01:02:31 PM »
Break will clean the dbl posts up if he sees this, it has happened before, his forum is broken,  someone must have loaded the best ejuice recipe in history of juice making..   :laughing:
-------------------------

Its on the bottom of the page left side, "Order Now" but first register an account.

heres the link for both

Register page:
https://oshpark.com/users/sign_up

Buy TriParaMos v1.0:
https://oshpark.com/shared_projects/TbLFzpbz/order


Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #235 on: March 01, 2015, 01:43:12 PM »
Break will clean the dbl posts up if he sees this, it has happened before, his forum is broken,  someone must have loaded the best ejuice recipe in history of juice making..   :laughing:
-------------------------

Its on the bottom of the page left side, "Order Now" but first register an account.

heres the link for both

Register page:
https://oshpark.com/users/sign_up

Buy TriParaMos v1.0:
https://oshpark.com/shared_projects/TbLFzpbz/order

Thanks Visus! I have them in my cart and have registered an account. Have to run now back to check out later. I like the mouser parts list to go with the board too very cool and conv!  :beer-toast:

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #236 on: March 01, 2015, 02:06:51 PM »
Question, can I use other N chan mosfets on this board?

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #237 on: March 01, 2015, 02:13:59 PM »
boards ordered just need to know if I can use mosfets I already have or not?

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Re: Tact switch and mosfet transistor questions
« Reply #238 on: March 01, 2015, 04:12:53 PM »
Question, can I use other N chan mosfets on this board?

That's a common footprint for MOSFETs.  It's based on a SO-8 layout.  Lots of SMD MOSFETs use it.  It goes by different names by different makers.  Vishay calls it PowerPAK SO-8, Ti calls it VSON-8.  Basically if you can fit an SO-8 package the leadless versions will fit as well.

The one he's selected is a good one, though if you plan to run down to 3V input, you're taking it right to the edge of the gate-source voltage versus on-state resistance curve.  For better performance at minimal input voltages you may want to select a transistor with a curve a little more to the left.

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Re: Tact switch and mosfet transistor questions
« Reply #239 on: March 01, 2015, 07:35:09 PM »
Craig
Need help  on this selection of MOSFET..  I know you have listed a ti fet b4³ but its buried somewhere.. 

Also on the ego boards using, they are usually pwm so using a cap/res as a low pass filter to keep the the MOSFET open  what would be a good shot in the dark without a scope to use as a cap and resistor..  Im searching for a calculator after I type this I know it's probably  one out here lol.. Im guessing 33.3hz like every other board out of China at that time then..  Im gonna try it.

http://www.ti.com/lit/ds/symlink/csd13202q2.pdf


Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #240 on: March 01, 2015, 07:50:17 PM »
That's a common footprint for MOSFETs.  It's based on a SO-8 layout.  Lots of SMD MOSFETs use it.  It goes by different names by different makers.  Vishay calls it PowerPAK SO-8, Ti calls it VSON-8.  Basically if you can fit an SO-8 package the leadless versions will fit as well.

The one he's selected is a good one, though if you plan to run down to 3V input, you're taking it right to the edge of the gate-source voltage versus on-state resistance curve.  For better performance at minimal input voltages you may want to select a transistor with a curve a little more to the left.

Craig would IRL3103STRL N Chan 30V 64Amps work? Thanks Craig You Rock!

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #241 on: March 01, 2015, 08:53:13 PM »
Hey fsors thanks for being interested in the mosfet board. Best of luck getting everything assembled and working once you get the boards.

IRL3103STRL is a different package D2PAK/TO-263 it's larger and won't fit on the pads. Also, RDS ON is fairly high. I would use a mosfet with RDS ON of 2 milliohms or less.
« Last Edit: March 01, 2015, 08:57:48 PM by david4500 »

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #242 on: March 01, 2015, 08:58:38 PM »
Hey fsors thanks for being interested in the mosfet board. Best of luck getting everything assembled and working once you get the boards.

IRL3103STRL is a different package D2PAK/TO-263 it's larger and won't fit on the pads for the mosfets. Also, RDS ON is fairly high. I would use a mosfet with RDS ON of 2 milliohms or less.

Thanks david4500, I will get the ones you have linked to the boards then unless Craig or someone thinks there is a better option. Really excited to build this. How did you solder the mosfets and fuses to the board?

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #243 on: March 01, 2015, 09:11:19 PM »
I would use a mosfet with RDS ON of 2 milliohms or less.

When/if I build a box mod I am going to use ur whole setup, ordering things from ti soon so wanted to try their mosfets,  the one I choose has about 7.5mohms at 7.4v  its not as important on reg but every bit does count.  You did heckuva research finding that fet it's lower than most I have found lil low on the amp side but three get ya 75A and uber low mohms so ya definitely the one...

I get confused looking at specs on fets but this one seems stout and I can try a sample..

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #244 on: March 01, 2015, 09:14:13 PM »
With a soldering station by hand. Hakko 888D with the stock chisel tip. Had it around 650F (maybe lower) most of the time. Bumped up to around 700F by some of the thicker traces. I watched a few video on youtube about hand soldering surface mount components. Basically, I got a bit of solder on the tip of the iron then tinned one pad for a component. Then applied flux (I used chip-quik smd291) to all of the pads for a part. Placed the part with tweezers, aligned as needed. Used a toothpick to keep the in place, then soldered the tab to the pad that was tinned. With the part tacked in place, carefully solder the remaining tabs or pins.
« Last Edit: March 01, 2015, 09:24:02 PM by david4500 »

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #245 on: March 01, 2015, 09:20:54 PM »
Visus, what project are you planning to work on if not a box mod?

TI might have some mosfets suitable for the pcb. I think they'd have to be reflow soldered since the tabs are all underneath the case.

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #246 on: March 01, 2015, 09:40:07 PM »
With a soldering station by hand. Hakko 888D with the stock chisel tip. Had it around 650F (maybe lower) most of the time. Bumped up to around 700F by some of the thicker traces. I watched a few video on youtube about hand soldering surface mount components. Basically, I got a bit of solder on the tip of the iron then tinned one pad for a component. Then applied flux (I used chip-quik smd291) to all of the pads for a part. Placed the part with tweezers, aligned as needed. Used a toothpick to keep the in place, then soldered the tab to the pad that was tinned. With the part tacked in place, carefully solder the remaining tabs or pins.

Fantastic david4500! I have a VV soldering iron and will give it a go when all the parts come in. This will go in a Box Mod of some sort. What are you putting yours in? Thanks for your help!!!  :thankyou:

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Re: Tact switch and mosfet transistor questions
« Reply #247 on: March 01, 2015, 09:45:50 PM »
I have some 1590Bs laying around, I'll make two mods with those. Should be plenty of room for everything. Could probably fit into a 1590G.
« Last Edit: March 01, 2015, 09:55:42 PM by david4500 »

Offline fsors

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Re: Tact switch and mosfet transistor questions
« Reply #248 on: March 01, 2015, 09:59:43 PM »
very cool, I was thinking about the same enclosures. I look forward to seeing some pics when you finish yours david4500 and hope you will post a few.

Thanks david4500!  :beer-toast:

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Re: Tact switch and mosfet transistor questions
« Reply #249 on: March 01, 2015, 10:48:54 PM »
Need help  on this selection of MOSFET..  I know you have listed a ti fet b4³ but its buried somewhere.. 

http://www.ti.com/lit/ds/symlink/csd13202q2.pdf

Also on the ego boards using, they are usually pwm so using a cap/res as a low pass filter to keep the the MOSFET open  what would be a good shot in the dark without a scope to use as a cap and resistor..  Im searching for a calculator after I type this I know it's probably  one out here lol.. Im guessing 33.3hz like every other board out of China at that time then..  Im gonna try it.

I'm not sure what you plan to use that MOSFET for, but that's 2x2mm package, it's very small and hard to solder by hand without at least 10x magnification.  I'm kind of confused on what you want you are asking.  If you can be more specific I can probably recommend something.

Are you looking to filter the PWM signal completely or just filter any noise out of it?  Normally you arrive on values for resistance and capacitance in a low pass filter by looking at the time constant.  It's simply 1/RC.  That specifies the period of the frequency reduced in magnitude by -6dB (reduced by half).  Typically you want your time constant no greater than one tenth the period of the frequency you want to allow and 10 times the period you want to block.  So if you want 33Hz to pass you need a time constant 3mS or less.  If you want to block 33Hz, then you need a time constant 300mS or greater. 

You decide on a value for R then set C based on that.  Depending on loading, you may be limited in how high you can go with resistance.  Obviously, the higher the resistance the smaller capacitance value you can use.  If resistance is low due to loading requirements, capacitance values can get quite high. 

Oh btw if you're not already aware, period and frequency are just two ways of saying the same thing.  Period is 1/frequency and frequency is 1/period.  Scientific calculators a have in inverse button to quickly do that and the one on mine is quite worn, use it a lot.


« Last Edit: March 01, 2015, 11:13:53 PM by CraigHB »

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