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Wow, thanks for the design! I didn't expect full solution for the problem, this seems more like paid membership.
I wasn't able to reproduce that in LTSpice (which we use in school), maybe due to component variations(I used LT1001 and general purpose NPN/PNP). Is that TinaTI?
I will try to...
Hmm, that sure works but I assumed that there would be a simpler way to achieve this. If it's 6 op amps, I really have to go with a microcontroller ADC. I wonder how the people did this in the 70s if voltage detection needs 2 op amps. Making voltage references for all of those would be hell.
I...
Hello!
I need to tap in some extra functionalities to resistor divided buttons.
Normally I have 5V:
0.6V when I press button 1
2V when I press button 2
I need to switch separate transistor for both buttons. The imput impedance also has to be high so that I don't mess up the internal voltage...
SIM800L UART(serial) level is 2.8V. You can see all the information you need from SIM800L datasheet.
There are boards with on-board 5V->2.8V TTL conversion for 10€, for example here:
https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=sim800l+5v&_sop=15
I don't think there is hardware...
I highly recommend SIM800L. It's a new chip, small size and modules are available for RIDICULOUS price.
You can get prototype modules for 7€ on ebay.
https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=sim800l&_sop=15
It works very well for basic operations such as text messages. SIM900 is...
Really? I think it has made some comeback in small devices, such as IoT. There's plenty of new simple SoC's that have integrated 8051 core.
The system is also simple enough to get familiar with general concepts of MCU architectures.
I think you shouldn't master 8051 anymore, but I think it's in...
So it prevents power supply capacitor(those big tantalums) charge flowing back into the battery? Did I understood correctly?
I'm going to power this using SMPS(12V car battery to 3.7V buck-converter), do you think the series diode is necessary for that? I don't think it's necessary, so I plan...
I don't have the module yet. I was asking so that I'd know that the power layout isn't rubbish. Now that I verified the purpose of those diodes, I will buy the module.
I will just bypass the useless dropout diode(I need low power consumption) and put some proper 3.7V input voltage directly. I...
Tunnel diode in Vsupply?
Hello!
I came across this PCB schematic of SIM5320E board, that has some weird diode configurations going on. There seems to tunnel diode to ground? What do you think?
The module in this schematic is rated "4.6V-5.2V" input, although the SIM5320E Vcc(after the diodes)...
Okay, thanks Klaus for the info. Atleast I know that using boost converter for a 12V solenoid is a viable solution. I just wanted to make sure there isn't a better method that I've never heard before...
I planned to power the entire boost converter using output transistor when needed. I don't...
Hello,
I'd like to ask just a quick sanity check question about my approach in my design.
I'd need to know what is the most reasonable solution to switching high loads, such as 12V solenoids/relays within low-power(e.g. battery powered) system?
I'm planning to use 3.3V MCU(to save idle...
Good point!
I realized that my UT61E multimeter has frequency option, so I probed CLK line and got solid 9.3MHz. The RTL8196C(the device's main IC) datasheet says:
So I reckon that 156/16=9.75MHz might indeed be the actual CLK frequency.
I attached CS probe, and suddenly I got some...
Flash chip too fast for 24Mhz logic analyzer?
Hello, just a quick noob question if I'm making the correct conclusion about this problem.
I'm trying to probe 75MHz SPI Flash using 24MHz logic analyzer(Saleae knockoff).
This is probably a dumb question, but I'm getting somewhat erratic CLK...
Oh right indeed! It's indeed in the sleep mode, I have CSCLK=2. I can't believe my absence of mind anymore. I'm glad that I don't need to switch the module because of this.
Thanks again, I need to take a break and see the datasheets and check out those power calculations. I think I can sort this...
It was actually also in "idle mode" with the 5mA consumption(sorry, I messed up the words). In this application the GSM modem must be connected to the network at all times, but everything else is sleeping.
I'm still dubious of that measurement of mine before. It was connected to network with...
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