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  3. Well, here are several very interesting circuits : Remote Control Blocker by IR More than once we will have spent watching the best scene of a strip and that we change the channel. To avoid these little surprises that we do not like so much we have this powerful team that will be in charge of "flooding" with IR signal the enclosure avoiding that the remote control of the TV or the equipment that was working properly. The circuit is more than simple, the PNP transistor oscillates at the appropriate frequency of the equipment to be blocked while the NPN transistor amplifies the voltage to apply it on the IR diodes. These diodes should be high performance for a better result.Adjustme Place yourself near the equipment to block and operate the equipment, turn the preset to find the frequency that prevents the operation of the original remote control. -------------------------------------------------- ---------------------------------------- TV transmitter This sensillo circuit allows to transmit the signal of a videotape or camera around the perimeter of a medium-sized house. It is very practical, for example, when you have a satellite television system and only one tuner / decoder is available. The same applies to boxes for premium channels of cable TV operators. Although it is also useful when you want to transmit the video signal from security cameras to hard-wired points. The scheme is very simple. The variable capacitor acts as a tuner, allowing you to adjust the frequency (channel) where you want to broadcast. Given the low power of this system the antenna can be a simple cable about 30 cm long or a retractable antenna. The transformer T1 is formed in its primary by 7 turns of wire while its secondary is composed of 18 turns. The 220pF capacitor connected in parallel with the secondary must be incorporated into the transformer last. This type of transformer is called SIF. As for the coil L1, this should be formed on a ferrite core of 3mm and on it should wind 4 turns of wire. Since this system operates with a very low power license is not required to use it, but if it were to place power stages that increase the scope of the set we recommend you to become a lawyer and become familiar with the legal aspects in force depending on the region where you go to use. Keep in mind that a poorly calibrated power stage could cause interference in the reception equipment of neighboring houses. Be careful in the assembly and calibration of this type of equipment. -------------------------------------------------- ---------------------------------------- 2w FM transmitter This transmitter is ideal for jealous girlfriends. Simply put it inside a teddy bear and give it to the poor boyfriend. Then, from a distance of approx. 300 meters depending on the complexity of the place, you can listen to transmissions with a conventional FM receiver. As long as the boyfriend does not listen to himself on a walkman, all is well. The truth is that, beyond the use that is given, this transmitter uses only two common transistors to broadcast audio through the commercial FM band. It is quite stable and the signal quality is sufficient to transmit musical or spoken audio. 30-40 MHz L = 8 turns on a ferrite core of 0.25 " Cx = trimmer of 15-20 pF Cy = trimmer of 10-15 pF Antenna = Wire of 38" 40-50 MHz L = 6.75 turns on a ferrite core of 0.25 " Cx = trimmer of 10-20 pF Cy = trimmer of 10-15 pF Antenna = Wire of 37" 90-100 MHz L = 6.5 turns on a ferrite core of 0.25 " Cx = capacitor of 5.6 pF Cy = capacitor of 3.3 pF Antenna = Wire of 20 " The circuit must be assembled on an epoxy printed circuit and powered with 9 or 12 v DC. It consumes 4w, of which 2w makes them irradiated power and the other two makes them heat. If you want to use the system with an electret type microphone, you will have to add a resistance of 1K from the positive to the negative terminal of the input capacitor (base of 2N3708), establishing the power that type of microphones require. Given its reduced power this type of devices do not require state authorization to operate. -------------------------------------------------- ---------------------------------------- 55w car amplifier Up to now, all the auto power circuits required a voltage source since these devices needed more than 40 volts. This circuit breaks with that tradition making it possible to manufacture a good quality audio amplifier for the car with only one integrated circuit per audio channel. In this way to make a stereo unit will suffice with two integrated and to make it quadraphonic will have to use four. As you can see in the diagram, the chip has everything necessary in its capsule, so it only remains to place the capacitors and filter and control resistors. Since the system is of the bridge type, the two speaker terminals are amplified, so none of them should be placed to ground. In any case, the circuit is protected against costs at the start, in addition to a long list of other protections. It is configured in class H. For more information about this chip connect to the page of Philips electronics, whose link is available in another section of this portal. The audio output does not require DC blocking capacitors as well as typical RL sets in these projects. It is possible to add a MUTE function which we omit in the diagram to simplify it to the maximum. If you want to do it, you have to place a 1K resistor between the ground and terminal 4, leaving the components that are as is. Thus the circuit goes into a mute state. By removing said resistor, the circuit returns to normal operation. Consult the specification sheet for more information about it. As in all these projects, heat sinks are extremely critical. Poor dissipation will cause the circuit to overheat and this will cause the system to shut down. It is not going to ruin because the chip includes internal thermal protection, but it will shut down causing it to stop amplifying. A Slot-1 or Slot-A microprocessor and fan (such as the AMD K7 or Intel Pentium III) is suitable, as long as the fan motor is running. In the case of using this type of forced cooling, it is important to design a good air channel since the fan is useless if it has no fresh air inlet and outlet. Another way to get good heatsinks is by making the sides of the cabinet the same heatsinks. In this case the size will be adequate and, in addition, It should be noted that this small "eats" 10 amps at maximum power so the power cables must be of adequate section. Otherwise they could be cut causing short circuits in the electric circuit of the vehicle. If you are going to mount four of these modules take into account the following: A medium vehicle has a 63 amp battery. This circuit multiplied by four consumes 40 amps. It is necessary to make a simple division to determine that it is capable of unloading the battery of the car in only two hours of use at maximum power. Therefore you will have to take special care as to see where the unit is connected. Another important factor is the ignition and fuel injection system. These circuits are usually somewhat sensitive to voltage drops so this amplifier can impair its operation. An alternative (very common in these cases) is to place a second battery housed in the trunk of the vehicle, which is charged through a diode from the voltage regulator of the alternator. Even the most expert of the engineers should take a tour of an installation house for this type of equipment because "the best hunter will miss a hare" and a mistake in the installation can leave it on foot. Do not even think about connecting the amplifier's power cord to the ignition key of the vehicle directly. Not even the key of a large truck could withstand the current. The way to connect it is simple, although it requires a relay. The contacts of the relay coil go in parallel with the current radio or pass tapes of the car, while the contacts of the mechanical key of that relay go in series with the cable (thick) that brings power to the amplifier from the battery. In this way the relay makes the brute force and the ignition key must only move the coil of the electromagnet. The relay should be able to handle up to 50A. It is possible to get one like this in the auto parts houses, asking for the one that switches the general power supply of the motor or the one that drives the starter motor. Another important point of the installation is the input signal. If the tape device you have installed in the car does not have line output, you will have to make an impedance adaptation and a power reduction to be able to connect the speakers' outputs to the amplifier's audio inputs. A good way is to buy a passive equalizer which modifies the tone of each band to equalize "attenuating" the others. It is important that this equalizer does not have an amplified output, because we would be at the starting point again. Although today most CD car kits have output without amplification. Another very common way is to place audio output transformers with the 8 ohm winding connected to the stereo output and the 2000 ohm winding connected to the amplifier input. It is necessary to clarify that although 1% of total harmonic distortion seems to be too much to be in a car it is somewhat low, given that the units that are commercialized normally have indexes of 3% to 5%. Only, just as they do with power, they lie about that value. Since the chip has a protection circuit against shorts that disconnects the output when the impedance of the load falls below 0.5 ohms, placing 2 ohms speakers (or 2 of 4 ohms in parallel) would cause the power to rise to 75 watts, but distortion will also rise to almost 10%. This is not acceptable for musical sound, but for propaganda or publicity on the public highway is ideal. Of course, the current demand will also increase. very good -------------------------------------------------- ---------------------------------------- Electronic Charger for Car Batteries Whether because we leave of using the vehicle for very long periods of time or because the battery is close to running out, this circuit allows it to be properly charged and indicated by means of an LED when the process has finished. As you can see the circuit is a conventional power supply, followed by an LM338 regulator which is controlled by means of an operational amplifier that is responsible for controlling the state of the load to detect the precise moment when it must stop and operate the LED indicator. The three-stage resistive divider allows, on the one hand, to take the reference voltage for the operational amplifier and, on the other, to control the LM338 regulator by means of the output of the operational one. In this way, the load cutoff occurs when the current drops below half an ampere, when the circuit begins to oscillate causing the transistor to conduct the current to the LED making it shine to indicate the end of the load. Note that the bridge rectifier is 10 amperes (voltage equal to or greater than 50V) so it is not for soldering in printed circuit but to screw to the metallic cabinet of the equipment and connect by means of crimped terminals. The initial filtering capacitor can be soldered on the plate or it can be enclosed in the cabinet by means of two plastic seals and soldered in parallel with the positive and negative terminals of the diode bridge. The general switch is of the type used in electric coffee machines which have inside the neon gas lamp that lights up when the equipment is turned on. Pay close attention to how this switch is connected since it is very common to confuse terminals and short the 220V line. The regulator LM338 must be mounted outside the printed circuit on a suitable heat sink of not less than 10 x 10 cm of surface. If desired, a DC ammeter can be placed in series with the positive terminal of the output to the battery to visually monitor the current status of the load. This instrument can be analog or digital indistinctly, although nowadays it is much more colorful a digital one. The positive terminal of the instrument is connected to the circuit and the negative terminal goes to the battery (towards its positive terminal). The resistance of 0.1 ohm must be mounted on the plate, but raised 2 or 3 cm from it to prevent the heat from disturbing the pertinax. It is possible to place a buzzer that sounds while the LED shines. To use it, just place the battery to charge, turn on the system and press the button that starts the charge. When finished the LED will light up and the system should be turned off and the battery removed from the terminals. -------------------------------------------------- ---------------------------------------- 90W amplifier Using only four transistors in a quasi configuration -complementary this amplifier can deliver 90W of power over a load of 4 ohms and at a really low cost. As you can see in the diagram, there are no expensive components in this circuit, except for the transformer of the source and the speaker. The input stage consists of two current drivers that directly excite the transistor pairs of the output stage. The latter (the 2N3055) must be mounted on generous heat sinks in order to preserve the useful life of these devices. When being fed by a simple source (of 80Vcc) to the exit of the final stage, before the speaker, a capacitor must be placed that blocks the passage to the direct current and only lets pass the audio signal. The source must be capable of providing 1.5A of current per audio channel. In this way a stereo power will require 3A to operate and one of four channels will require 6A. -------------------------------------------------- ---------------------------------------- Well, this is all, Note: maybe some of the circuits have not been tested. in case you need some other information, more circuits or something, ask for it, but here is the source, where there is more
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  5. Bag Housing
    We have been in the bag filter business for over 35 years. Stainless offers significant benefits over standard carbon steel.

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  7. Yes, you can buy basic TTL Chips from Digikey or Amazon. BTW here is the closest I could build up to your specs. I did not use the 7432 OR gate though. Just made a 5 input 7400 NAND gate. When the output of x1 x2 x8 x16 x32(∑=59, because the base10 is one less than the MOD# ie mod#-1=Base10) goes active HIGH activates all the AND gates to go High. When this happens it activates the NAND gate to be a LOW state. This causes the clear inputs of the 7476 JK flip-flops to clear and start the count at 0. Also, please note that the least significant bit(LSB) is on the left, and the Most significant bit (MSB) is on the right.
  8. This is regarding your product "USB Adapter board for kiosk computer" and the software that comes along with it, "Panel" I bought 30 of them and I needed more, however there was a problem with the software that came along with it, the email feature and from time to time it doesn't give credit to the time after inserting coin. The email feature doesn't send an email and actually it gives error if I will do a manual test to send an email to the email address that was assigned to received the email report. I spoke with your supposedly technical support over skype, skype id Frank, and promised me to get back at me to look into the problem, that was last August/September but until now I never get an answer from your company. Maybe through here, electronics-lab community someone from your company would provide me an answer.

  9. LED

    Can you be more specific on what you would like to achieve?
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    how to control frequency of the 230v AC
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    1. audioguru


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  14. Hello. I'm building a 12v bluetooth speaker and am trying to design the battery and charging system. I'm thinking about using 3 of the Panosonic NCR18650B in series to start, and then perhaps upgrade to another 3 pack in parallel later if the battery life isn't good enough. This is my first experience building something with Lithium batteries and it's a bit intimidating. I've done quite a bit of reading, but i wanted to come here and ask a few questions in hopes of getting this right the 1st try. more: eco dream city The BMS i've chosen shows "charge/discharge" on one of the images for the P+ and P- terminals. I'm hoping this means that I can connect my incoming power AND my load (12v amp & bluetooth module) to those terminals and it will allow me to use the amp while charging. In the description it says "Charge with 12.6-13.0V Power supply (not included)." With that in mind, here are my questions: 1) I was working under the assumption that i would need a battery charger or charging circuit before the BMS, but the description makes it sound like i can just put a power supply directly to the BMS. Would one of the 12.6v li-ion plug-in style chargers (like this one) be ok to use with this BMS? Would a charger like that cause interference noise in the speaker? more: dự án mỹ đình plaza 2 2) When connecting the power and load to the BMS, do i need any kind of diode in line with the load? 3) I was planning to get the protected versions of these batteries, but is that necessary if i use the BMS and charger that also offers protection? If I was to use the protected batteries, does that eliminate the need for the BMS? I have built NiMH chargers using the Maxim ICs in the past that allow for charging and load as the same time without any interference, and I know that option is available for Li-Ion as well. However, i would REALLY like to avoid making my own charger if possible. more: dự án eco dream Thanks for any advice you can offer!
  15. Hello, The following below document (RDR-32) is for a 150W PFC’d LED streetlight. Its noticeable that the schematic on page 8 simply shows the earth connection being simply connected directly to the neutral. Surely this is not wise as RCD’s could be tripped? more: mỹ đình plaza 2 Surely for the sake of common mode noise mitigation, it would be best to have Y capacitors from live and neutral being connected to the earth connection? The schematic on page 8 shows no Y capacitors in the mains input section. Isn’t this a missed trick? Another point is that in a streetlight, the pole itself is earthed, and the streetlight head itself is inevitably metal and is directly fasted to the earthed pole. In other words, the metal casing of the streetlight head is also earthed. It surely makes sense, to use the metal head of the streetlight as a heatsink. –If one does not do this, then one has to isolate the metal head of the streetlight from the earthed pole, and surely this is a waste of time? more: chung cư pcc1 triều khúc Anyway, the RDR-32 document never speaks about using the earthed streetlight metal as a heatsink. Indeed, for the PFC stage, it recommends heatsinking the Boost FET and diode bridge to primary side DC bus ground. –Surely this is missing a trick?......i mean, you have a big chunky metal streetlight head, why haven’t they used it is a heatsink? Is it because they fear getting more common mode noise if they use an earthed heatsink for heatsinking the power switching FETs? Even then, surely it would be best to still use the earthed streetlight enclosure as a heatsink, and then just use a bigger common mode choke in order to mitigate the common mode noise problem? more: eco dream nguyễn xiển I mean, they have a big metal streetlight..why are they not using the streetlight superstructure itself as the heatsink?...i’s going to be there anyway. I appreciate that its earthed but earthed heatsinks are not at all uncommon.
  16. Introduction

    Thank you guys, for such a warm welcome.
  17. OEMsecrets Partners with Retronix to enable IC Testing services. Retronix are considered to be one of the industry leaders in IC testing services. They offer a unique set of technology solutions and can test any components you purchase whilst also offering alloy conversion if you cannot find your part in the specified alloy. To support obsolete components listed by verified non-authorised distributors on OEMsecrets, users can now request testing services by clicking the "IC Test" icon, located in the specs column of the search results on OEMsecrets is a free to use price comparison search engine for electronic parts and components, listing inventory and pricing information from suppliers such as Avnet, Arrow, Digikey, TTI, Farnell and many more. Learn more: &
  18. I ordered my first PCBs from last week, and I am very impressed. I usually get my PCBs from seeedstudio ..... but now it will be JLCPCB. It's my firist order. Unimaginably, my first order , shipping ,free !!!! Just cost $2 !!!! Can't unbelive this. I order the senond, shipping ,display $18 to Candan. The customer service told me: free shipping just for first order. Here is quick review, in point form; · Great web site and is update. Can actually see PCB manufacture process of order, tracking, design, etc.. everything is in one place. Nice. · 5 days to arrive at my door, from time of order. I am in Candan.· PCBs packed very well. · Silks screen is very detailed and 'fine' · Price is the cheapest... · Shipping is with DHL, which i like. I like red I have a new try and choose a red mask. I like red, it’s bold and eye-catching. Green with white is probably the best of all the available colours in practical terms. Below boards from JLCPCB. They were all cut perfectly to size, all perfectly etched and drilled, tinned. Inspection of fine traces on the board for defects is best done with some form of magnification. Electrically, the SIMM tested fine.
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  20. 0-30 Vdc Stabilized Power Supply

    The original project had many overloaded parts including the power transformer. It used TL081 opamps but your TL071 opamps are simply TL081 opamps selected fo low noise (audio applications). Their absolute maximum supply volyage is 36V but this project with a 24VAC transformer produces about 25VAC when the load current is low then its peak is 35.4V which is reduced to about +34V which is the positive voltage for some of the opamps and -5.6V is the negative supply for them. Then they get 34V plus 5.6V= 39.6V which is too high for these opamps so they will fail soon. The improved modified circuit uses opamps rated at 44V and the -5.6V supply is reduced to -1.3V. Of course the output transistor gets hot when loaded, even with a huge heatsink because it and the driver transistor are overloaded. The improved modified circuit uses a better driver transistor with a proper case that can be bolted to a larger heatsink and TWO output transistors are used to share the heat. Use a fan if you want. It is easy to find a table of wire size and the current it can handle, and use Ohm's law to calculate its voltage drop. Use #18 AWG wire and solid core or stranded are both able to carry many amps of current with a low amount of voltage drop. The overloaded transformer is rated at 24V x 3A= 72VA but needs a transformer that is 28V x 1.414 x 3A= 119VA instead then its voltage will not collapse when loaded. But then the 44V opamps must be used. It should be obvious to you that when the current setting is set low (you cannot turn it off) then any load current higher than the setting will reduce the output voltage. It should have excellent voltage regulation. If the current setting is 2A and you load the project with 1.5A then the output voltage might be 25.0V with the load and the voltage set to 25.0V and when the load is disconnected the voltage might rise to 25.005V, or be 25.0V with 2A and drop to 24.095V without a load.
  21. Introduction

    Welcome Lake Shore. is one the best electronic forum community. Thanks.
  22. 0-30 Vdc Stabilized Power Supply

    I created the previous build for this project from this link : I couldn't get the required TL081 so I replaced it with TL071. Now the circuit works well and good. But I have some doubts : 1. The power transistor 2n3055 is connected to a massive heatsink, but the wires drawn from it are single lead wires. Im not sure of how much current it can carry. I did test the PSU using a 100 ohm 5a rheostat and found the transistor heating up. But even at 3a in the output, the wires drawn from the transisitor didn't burn off. I didn't test it for long duration. so my question is what wires should I replace in the connection. is the single lead wire capable enough to carry 3a? should I get multi threaded wire? If so, of what guage? 2. the PSU when loaded using rheostat couldn't reach the peak voltage of 30v. as soon as the rheostat was connected , the output voltage dropped to he range of 20-22v. Is there any way I can hold the output voltage in the value I deserve? or did the output voltage drop so as to limit the current using the current limiter circuit(which was not turned on when loaded, current knob kept at zero position. 3. how can I test the current varying capability ? at constant voltage obviously... help out a brother... cheers
  23. 0-30V 0-3A Latest Data Discussion

    No, it is a power supply, not a charger.
  24. 0-30 Vdc Stabilized Power Supply

    No, it is a power supply not a charger. Then this modified power supply project will have a maximum regulated output of only about +25V at 3A.
  25. 0-30 Vdc Stabilized Power Supply

    Is it possible to charge 12V 18AH (Sealed Rechargeable UPS ) battery with this Charger ? In past i have blown 0-30V / 0-3A LOADSTAR PSU while charging this battery. Thanks Ahead I have a 24V, 10A transformer. Will this do the job. Thanks audioguru
  26. 0-30V 0-3A Latest Data Discussion

    Is it possible to charge 12V 18AH battery with this Charger ? In past i have blown 0-30V / 0-3A LOADSTAR PSU. Thanks Ahead
  27. I am new to both this site and electronics, and everything I know about components and how they work (which is near non-existent) I have learned in my spare time. I am planning on buying a modified sine wave inverter to have for emergencies and to power miscellaneous items in my car. I don't plan to use it on anything with electronics, because I know that they don't always play nice together. Knowing that capacitors help smooth voltage (at least I'm fairly certain anyways) how would I calculate the correct capacitance for a known load? This would be partially for increasing efficiency and also incase I am at a job site and need to recharge my power tool batteries. Also, if anybody could explain to me as to why I always hear that modified sine wave fries battery chargers, it would be greatly appreciated...actually any information even remotely related that is explained in laymens terms would be very helpful. more: chung cư eco dream, bán chung cư mỹ đình plaza Thank you to anyone and everyone in advance that can help
  28. After recently becoming somewhat broke, my wife and I were forced to settle in a small town in a very Wild-Westy part of New Zealand: Deepest darkest Southland. Like many of the inhabitants of this hillbilliyish community, our hard-smoking, hard-drinking, benefit-frauding 'neighbours' on the north side, are unable to function without a constant diet of loud 'music'. more: dự án eco dream (I use the term 'music' in the loosest possible way. It's just repetitive, thumping noise) I won't detail all of the hoops we've jumped through to try and get this racket to cease. Suffice to say we've exhausted almost all options, except, of course, moving elsewhere. We can't afford it. more: chung cư mỹ đình 2 However, it occurred to me that, as these trogs like their noise so much, it might be helpful if I were to amplify the waves that beam over the fence, and feed it back to them. I have a fairly powerful amp and a few spare speakers, but I'm sure I can cobble together something else if it's required. Advice will be appreciated. more: chung cư eco dream city
  29. Internet Radio

    Could you please provide the frequency band? I am interested to use internet radio. Is it like the normal radio or having some special feature? Also provide a link that I can access.
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