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Beginners / Re: Op amp based projects suggestion
« Last post by ChrisGreece52 on Today at 01:10:05 PM »
Hey i found not long ago this sine wave generator using op amps you can get a dual one and build it it does not take much time and its a good project for starting using op amps.
You could also build a comparator but as i was suggested in this right forum you better buy a real comparator if you are going to use it for a project :P

Hope i helped you
Since the design get's a whole lot more complicated with the LM393, and some sort of push-pull circuit, would you recommend any rail-to-rail dual comparator for this project?

What's you preferred source for components? There are literally tens of thousands of potential parts, I don't think me saying any particular one is particularly helpful. But FWIW, from digikey I'd look at the MCP6542 as a starting point. 1.6V - 5.5V operation range, 2mA output guaranteed (depending on your application, this is plenty to drive a quality LED, and there's an absolute max of 30mA so you can look into seeing how the output would sag for higher drive currents). And it's a dual device, so you only need one part. US$0.57.

...flickering PWM  ;)

Stating the obvious: PWM doesn't flicker if you use a sensible frequency.
Not going into the obvious why some knowledge should and must not be shared.

But I have met too many people that are simply too lazy and asking very lazy questions that they could have found out by doing a basic search and readup.  It is simply waste of answerer time.  A display of no respect of other people time.  Answering these types of question likely cause more harm to the people that asked as they likely to not break out of that mode of behaviour.
Other Equipment & Products / Hakko 888 vs 951
« Last post by mtdoc on Today at 01:06:07 PM »
How much of an upgrade is the 951 compared to the 888? I have an 888 but am looking at getting a second iron and want to upgrade as well. I don't think I can justify a JBC class iron given my hobbyist level use, but then again if the 951 is not a big upgrade from the 888 maybe I don't need it either. :-//

Opinions from those who've used both appreciated.
Crowd Funded Projects / Re: Shaving with laser?
« Last post by EEVblog on Today at 01:02:50 PM »
A writer for CNet got a hands on with the prototype:
But when I lifted the razor to my arm and placed the fiber against a hair, it cut right through. The laser actually worked. We tried it with light hairs and dark hairs, over and over again. Twice, we accidentally broke the fiber by getting the cheese-wire style blade caught on several hairs at a time, which definitely gave me pause
Skarp co-founder Binun says that with a mass-produced fiber and a AAA battery, the razor should have enough power to cut through five hairs at any given moment and keep cutting through more as soon as the previous ones fall away

Wow, so even the final design will only be able to cut through 5 hairs at a time!  :palm:
Newsflash - people are hairy, razors are required to cut through hundred of hairs at a time!
The average mans beard contains thousands to 10's of thousands of hairs.

Yet another stupid impractical product idea.
Google search of "ESINOMED infoview" gives no results, that had existed before Eevblog video. This crap tablet was probably never sold at market.
But hey, there was another crap product from Germany. Do you remember the Welec oscilloscopes??
General Chat / Microchip Technology (1983)
« Last post by Homer J Simpson on Today at 01:01:37 PM »

Beginners / Online electronics vendors
« Last post by ChrisGreece52 on Today at 01:00:19 PM »
Hello again :D almost finishing the theoretical part of my project and i am almost ready to start shopping for parts.But i am not sure where from

I usually buy components of ebay because there is free shipping for Greece and tayda electronics because they have a vast selection of parts and reasonable shipping charges

But in my project i use the 74HC390 and i could not find a bunch of through hole chips from one vendor only smd ones.
I need some online electronics vendor suggestions with low shipping costs (if not free then reasonable) because i cant use element 14 or digikey because the product cost would be around 10 dollars and i would have to pay 40 when the shipping charge is added.

It would be nice to be one place where i can pick everything i need instead of just the ic. ( Like tayda)
Anyway thank you for your suggestions in advance :D

My car insurance company (Admiral, in the UK) contacted me and asked if I wanted to receive a 'box' that would monitor my driving and possibly reduce my insurance premium. I agreed. It only had to be kept in the car for 3 months and then returned, and since I only used my car for commuting, I didn't mind them effectively tracking me. After all they already know where I live and work.

I received the unit pictured below:

Two main components, the power adapter, and the circular "puck". The latter came with an adhesive pad on the back, and the manual noted to mount either flat or at vertically at 90 degrees with the arrow imprint always pointing forward. I assumed it contained at least an accelerometer and gyro to record my driving behaviour, as well as a GSM radio to send the data back to their headquarters for processing.

Of course, being the inquisitive and aspiring electronics engineering nerd that I am, I had to take it apart! I waited until after the insurance company asked for me to send the unit back before taking it apart, in case disassembly produced some weird results and skewed my data, or there were some internal switches pressed against the case that could tell when the unit had been opened or tampered with (spoiler: there weren't any).
Now let me state here, I'm pretty much an electronics noob. I understand what most of the components are and do on the boards, but I have some questions that I'll post at the end if anyone feels like teaching me something.

I'm really posting this because when I originally got the unit, I did a quick search online to see if there was any info about this particular unit and what exactly was in it, but failed to find anything. Hopefully this post will be found by someone else like me in the future, who wants to know what's inside this box before they stick it in their car for 3 months.
I know this is also the same box used by Bell Insurance, and presumably also Elephant, Diamond and Gladiator Insurance, as they are all within the same group, although I don't know if they offer a telematics scheme.

Teardown: (Click images for full size versions)

Puck PCB Top

Puck PCB Bottom

12v Power Adapter

  • Identifying marks hidden in photos.
  • Contains GPS and GSM units (datasheets linked below), and presumably an accelerometer/gyroscope and magnetometer (I'm unsure where these components are).
  • Large shielding can under the angular antenna, unfortunately i didn't want to risk trying to pop it off without damaging the unit. Would have loved to see under it.
  • Unit was powered up while taking these photos. Notice the green LED on the puck.
  • There is a quite a significant amount of bodging done on the power adapter PCB. Mostly diodes and a couple bodgewires!
  • Power adapter has a completely blank PCB backside
  • Power adapter has 2x AAA rechargeable batteries under the PCB connected to the white JST connector on the top side. the device is always powered until they die. There is no off switch.
  • The power adapter has a switch on the centre pin of the 12v socket plug, allowing it to recognise when it is physically unplugged from the car.
  • Power adapter also has a USB socket for charging external devices, and a secondary 12v connector (black plastic plug on the bottom edge, under the USB socket) for an included optional 12v automotive socket on a short wire
  • Interestingly, the patent explains how the unit 'profiles' the car's electrical system (presumably electrical signal noise from the alternator) and recognises if it's being used in a different car.
  • The patent proprietor is listed as the insurance company, so I assume they actually invented this particular model.

My questions are:
  • Where is the processor? Under the can?
  • Where is the accelerometer, gyro and magnetometer?
  • Since the unit has a GSM radio, does it also need a SIM card? Where is the SIM?
  • What do you think the 3 pin jumpers are for, on the top of the puck?



Code: [Select]
btree_ans_t p_btree_coin_leaf_find
    p_btree_t p_btree,
    uint32_t coin
    btree_ans_t       ans;
    p_btree_node_t    p_root;
    btree_node_addr_t i_root;
    uint32_t          i;
    boolean_t         is_done;
    boolean_t         is_found;

    i_root = p_btree->context.i_root;
    p_root = get_address(p_btree->context.node.p[i_root]);     = (p_root->item.n isEqualTo 0);      = False; = False;

    if (p_btree->context.node.p isNotEqualTo NULL)
        i       = 0;
        is_done = False;
        while (is_done isEqualTo False)
            is_found = (p_root->[i].coin isEqualTo coin);
            ans.addr = i;
            is_done = (i >= btree_node_item_N);
            is_done = (is_done logicalOr is_found);
    } = is_found; = is_found;

    return ans;

the above is not for my job, it's hobby, but I wanted to exercise myself with the same "conforming code", and ... it happens to pass QAC

first observation: the conforming code is bloated, you have to write more code
second observation: after 4 weeks I am still able to understand what the frog I coded
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