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Alex Tsekenis
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Posts posted by Alex Tsekenis
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Who is the project for?
GPS will not work as you are in a building. It might work but the accuracy will be low and sometimes you will lose signal.
Does the building have wifi coverage? -
We have a problem as many pages are missing. From other topics too.
I can't think of a reason to have max volts/amps.
Maybe we could say CC/CV for each channel? -
Hero is right, we need the schematic of the XP-720 power supply. Also I dont know if you have noticed Hero but the current sensing resistor is connected to an LM337, not an LM317, which makes this a very weird circuit.
I bet S1 and S3 cost nearly as much as a second DK203. -
allowed a max of 500ma this should more than enough,I'll rate the reference power supply to 250mA
You will probably find that less current will be needed. Most of this will be going to the LCD backlight, about 20mA. Digipots will draw about <1mA (excluding resistor ladder). Dual or more versions can be found. The MCU itself needs not run off 5V (the LCD accepts TTL signals). It can run at 3.3 and at relatively slow speeds like 1MHz. 20mA will be a conservative guess. -
You have accidentally attached a much earlier asc version.
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This is great Hero, as you say the charging of C1 is evident as it is during a normal star-up.
I agree, the recovery profile is not too important. I see that the under/overshoot is minimal.
Could you also run a sim with the load changing from 10% to 100% and back? That would be important. Also, please post the asc you are working on. -
I thought you posted that as a topology example as you had also already mentioned using -0.6V. But PICMaster copied that in his simulator. Maybe that's why you got even worse result PICMaster.
So we have decided to include a small negative supply to get the output to zero. Hero, will you look into a balanced positive/negative or +V+6 and say -0.7V?
The question now becomes whether there is a way to minimise the component count of the power supply's power supply. -
Do you want to build it entirely on your own, or buy a few systems and put them together?
What will the strain gauge be used for? -
What is Steorn's main funding source?
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Can you create a negative voltage without using a doubler with the way the centre tap is connected?
D3 and D4 route the negative half cycles to ground potential and the centre tap is connected to V+.
I dont think it's possible. Using a doubler to create just about -0.7 volts sounds overly wastefull to me..
[glow=red,2,300]EDIT:[/glow]I have added the -9 supply and to me makes it worse,
That would exceed the LT1014 dif supply voltage by 5 volts! -
Maybe we can look at charge pump inverter for the op-amp supply, like the one attached. This config offers a -Vin and +2xVin.The only problem is tha te maximum Vin is 20VDC so some sort of preregulation will be needed from the V+ line.
Edit: Wouldn't adding a resistor from Iout node to ground form a pot. divider with R23? Maybe you can change the gain of the dif amp.
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Use an online translator like babelfish to translate your post to English.
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If this is for personal use, I am sure you can find the SW from somwhere.
If this is for professional use then the cost can be justified and expensed.
If this is for personal but professional use then it is up to you to treat it as just personal or just professional use. -
I agree, I would have hoped it would be lower but I looked at the datasheet and the worst case is 25mV, 10mV is typical and 5mV typical with 600R resistor.
Can we add a negative offset? -
Why digital pots
I feel that they are the least intrusive. PWM is the other obvious way.Alex what language do you write your code in ?
C is my language of choice. Cad do several others if needed. -
www.ni.com
www.mccdaq.com -
All of these can be changed in user preferences.
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So much information...I was only away for like 3/4 of a day!
I would overrate the outputs (I, V) slightly to ensure that despite tolerances we have 30V, 5A.This has shaken my confidence in LTSpice.
Welcome to the club.Will there be a LED for the visual indication for over current...
I think adding LEDs and indicators is trivial and could be left for later on.I expected the minimum current setting to be 25mA maximum
Pretty high?I was also thinking would it be better to have the bridge rectifier and cap mounted of the PCB, This would save people hunting the right Cap & rectifeier and aslo reduce the size of the PCB.
IMO the best of both worlds would be to put multiple cap sizes on the PCB. The same for some other components.
On a different note, I was thinking of the digital front end. An I2C bus would be nice as we can hang all digipots on it, plus say a temp sensor or a fan controller.
Thanks for the latest asc file. PICMaster, you have a relay in your schematic ??? Sorry I can't spend more time on this despite wanting to. -
physical dimensions of the composite block
We need to know that to calculate the current flow since you have an estimation of conductivity. Good luck! -
Hi I must have confused you..UPS 600VA are normally used for computers, and I am thinking if it will have disadvantage if I will use the UPS in different device. I want to use the UPS as supply for a device that will consume only 10-12 watts. I will use a power supply
adaptor with 12V 1A rating plugged in UPS for the device. Will the power supply adaptor easily be worn out if I will use it with UPS? Thanks for the quick reply by the way
Ok.Decoding the post I think you mean that you have a 600VA UPS, normally used with a PC, and you want to connect a small wall transformer to it to power some device. The wall transformer is rated at 12V 1A.
Yes, you can do that. The transformer's primary will most likely be rated for the same volatge output as the UPS.
You will be able to use your transformer for about 40 times more time than a 600VA load.A new LCD monitor uses about 20VA..
For some reason my right Samsung monitor says at the back: 240VAC, 1.2A.
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By diagrams I think you mean circuit schematics.
EAGLE is prob the easiest, and common, software to import schematics and then transfer them to PCB.
Multisim can also be used and it also offers a simulator and PCB design.
TINA as above.
Altium (also Cadence) is by far the best package you can get your hands on. It might take you a while to master, but you can import schematics, simulate and do PCB design in the most convenient way.
LTSpice is also good. Apart from not having a PCB editor integrated I find the user interface a bit time-wasting.
Some of the above are free or partly free.
There are also two packages to import designs as if they were on a breadboard or a stipboard. If you are interested I will look for the names.
You must be joking with MS-Paint or MS-anything. -
Which one is it? T4, 5, 6, 7?
http://www.abb.co.uk/product/seitp329/2deffbcd59f95e48c1256ed20037f66d.aspx?productLanguage=us&country=GB&tabKey=2
I think the best thing you can do is contact an ABB engineer for support on this. It's free. -
Are you talking about finding a transformer which will allow 0 to 30V @ 5A?
Yeah, that is what I meant. Since using a higher volatge trafo will require more parts, in the final project it would be nice to have a trafo that can offer 5A without output ripple.If most people here decide it's a must, then I'll look at redesigning for a 30V transformer. This will probably mean ditching the LDO MOSFET idea and going back to a more traditional transistor based approach.
How about arranging for the zener diode regulator across +V+6 and ground by increasing the zener voltage and recalculating the resistance? This will waste more power on the zener (series diodes?) but will allow a 30V trafo and you get a regulated supply for the op-amp.I have to justify the space they take to myself...Put them on ebay?
I tried in the past. The problem is that most people buying from ebay can't afford them and those who can, don't buy from ebay if you know what I mean. Might try again in the future.I've decided on the IRLZ34N
Anything. That is one cheap MOSFET btw..RS is cheaper for the 10,000μF
Anything than a single 22000uF/63V cap.It's probably a good idea to put footprints on the PCB for two capacitors as well as one and different diameters if convenient.
Good idea since this is a kit.I would have thought simulation would be good enough since the simulator performs loop analysis anyway.
Can LTSpice do Bode plots? I am asking, I don't know. We can optimise some of the components this way but as you say good enough. We can simulate some reactive loads too later on.Surely it's more cost effective to use one voltage reference IC and obtain other voltage references using potential dividers?
Sorry, I get confused with multiple sources on the diagram.The original idea was to use an LM78L05 but then I decided the tolerance is too wide.
Good thing you rejected that.Now I'm thinking of using an LM431B which has a tolerance of 1%. I could use the C version which is 0.5% but it's probably harder to get hold of and will be more expensive.
It is not like we have much choice in TO-92 at this tolerange range... I looked on RS and Farnell, most products are the 431 from different manufacturers ::) 1% sounds reasonable. We should consider how much effect on the output a 1% reference error will have compared with using 1% resistors for the potential dividers. That said, TI's TL431 says A=1%, B =0.5%. The TL431A costs only 30p on Farnell and you dont have to buy a bag of 50 like on RS.
How about the LM317L? Just an idea. Never mind, the 1.25V bandgap reference is at +/- 0.05 V i.e. 4%.I'm thinking 1% for all the gain and reference setting resistors and 5% for everything else.
Close tolerance is nice but <1% starts to get expensive and harder to get hold of.
Fully agree, 5% can also go for R16,17. 1% resistors are used more and more frequently so if we say 1% throughout I dont think the cost difference would be prohibitive, if any. It saves the effort of saying this 5% that 1% etc. -
I am just looking at the asc file.
Maybe you should separate Vref for the current limit and use a third source for R12/R13. In fact, how about using a constant reference for U4 as that doesnt need to be variable. How about a circuit around D8?
Current limit attack time? Are we strategically ignoring this at the moment?
Also, I noticed you used a time dependant current source as the load. I think a resistive load would be better as it is completely passive. The way I have done this before was to use a time dependant voltage source to connect low value resistors to the output through a MOSFET. I am sure there is a better way to do this.
Finally, I see you added ESR (50mOhm) to C1, not C7 as I was asking in a previous post. I was thinking that that 400+A short circuit current might have been due to the 0 ESR for C7.
EDIT: The output voltage now seems to be 6*Vref. Any ideas what happened? Also, what is the output impedance of U1 in this configuration?
locator help
in Electronic Projects Design/Ideas
Posted
I can bring you in contact with an IT services company that amongst others, do location tracking based on WiFi mesh networks and watch-like wearable units. They originally developed the system for security personnel in open-air events. Interested?
Edit: I see this is not for a professional application so I am not sure if this is the way to go about it. Still, let me know if you would be interested in them putting together a demonstration system for you guys. Unfortunately I am not aware of any way of doing what you need from the top of my head.