hybridfree/eevblog-posts huggingface dataset:
6502/65C02 CPU emulator, TMS9918 VDP emulator, Character/graphics LCD emulator - Page 1
Forum section: electronics / projects

author: visrealm
author_rank: Contributor
timestamp: January 30, 2022, 01:33:00 am
content: Hi all.Have been working on a few emulation projects to support my6502 on a backplane (HBC-56)emulator.They're all written in C99, have no dependencies, open source (MIT license). You might find them useful for your own retro computer emulation projects.CheersTroy6502/65C02 CPU emulatorSupport for standard 6502, 65C02, WDC65C02 and R65C02.All WDC and Rockwell-specific instructions.Correct handling of Decimal mode.Accurate instruction timing.User-supplied I/O callbacks.IRQ and NMI signals.Multiple CPU instances.Instruction disassembler.Passes all Klaus Dormann 6502/65C02 tests.GitHub link:github.com/visrealm/vrEmu6502Character / graphics LCD emulatorSupports 1, 2 and 4 row character LCDs.128x64 graphics LCD support.Built-in WASM build with HTML5 renderer.GitHub link:github.com/visrealm/vrEmuLcdTMS9918/TMS9918A VDP emulatorSupports all documented modesGraphics I (including sprites).Graphics II (including sprites).Multicolor mode (including sprites).Text mode.16KB VRAM.5th sprite.Sprite collisions.VSYNC interrupt.Individual scanline rendering.Supports beam-racing effects.GitHub link:github.com/visrealm/vrEmuTms9918
6550 tube amplifier diagrams - Page 1
Forum section: electronics / projects

author: luiHS
author_rank: Frequent Contributor
timestamp: January 09, 2024, 03:12:53 am
content: Hello.Quite a few years ago I bought all the components to build a Class A tube amplifier with 6550 tubes, 25W.The fact is that the same book shows the schematic for the 50W version, which adds two more 6550s in parallel and changes the output transformer.What catches my attention, and I don't know if it could be a book error, is the way of connecting the 12AT7 preamp tube to the 6550, which is completely different in each scheme.Could someone tell me if these diagrams are correct?

author: Andy Chee
author_rank: Super Contributor
timestamp: January 09, 2024, 03:46:47 am
content: From my non-tube background, it appears your four tube schematic has independent biasing for each tube.Apart from that, the 12AT7 is now a cathode follower (probably to deliver enough current drive for four tubes!)

author: floobydust
author_rank: Super Contributor
timestamp: January 09, 2024, 03:53:53 am
content: Both look correct.The 25W uses a driver stage with voltage gain, the 50W uses a cathode follower for the heavier (4 vs 2 6550) load and this config has no voltage gain (it's 1) - so there is an extra gain stage with the 12AX7 ahead of it. The 25W only has one gain stage with V1.
65C02 / TMS9918A homebrew breakout clone - Page 1
Forum section: electronics / projects

author: visrealm
author_rank: Contributor
timestamp: March 01, 2022, 08:10:17 am
content: Just started working on a breakout clone for my homebrew 65C02 build. Mainly to have a go at working in the TMS9918A's Graphics II mode beyond simple demos:As always, all source code (65C02 assembly) is available:https://github.com/visrealm/hbc-56/tree/master/code/6502/breakout. The schematics, emulator, etc are all in the github repo too.

author: visrealm
author_rank: Contributor
timestamp: March 02, 2022, 07:54:35 am
content: Previously, my web-based emulator ran BASIC by default and you could drag ROM images into it. I've just added support from loading server-side ROMS, so now you can try it yourself... in your browser:https://visrealm.github.io/hbc-56/emulator/wasm/?rom=breakoutA couple of limitations:1. Audio doesn't work in the web-based emulator.2. You will need a keyboard.Oh, I've also cleaned up the code:https://github.com/visrealm/hbc-56/tree/master/code/6502/breakout
65W USB PD3.0 (Power Delivery) solution - Page 1
Forum section: electronics / projects

author: MrMetthew
author_rank: Regular Contributor
timestamp: July 03, 2020, 10:46:59 pm
content: Hi guys,I am working on a new product. The product has a need for USB PD3.0 power delivery on a USB c port. I have no prior experience on implementing USB Power Delivery and wanted to see if anybody has some good ideas while I am further studying the topic myself!Essentially the solution I am still deciding on is a USB PD3.0 power delivery solution. Essentially our device should act as some sort of USB hub in this regard and must deliver a minimum of 65W to one upstream USB-C port, confirm USB PD3.0. Our device should act as an USB PD source only, no sink capability needed.Our device will have an DC power rail available to feed the circuitry. Something like a pre-qualified 20V-5A wall brick. These values are not set yet, for example it might make sense to have a higher voltage brick so the PD3.0 implementation can be done with a buck topology only. But I would need to see if we can get that to be compliant. So, for now I am favoring a more flexible buck/boost topology.So basically I am searching for parts/topologies to make the PD3.0 work. A USB PD3.0 Controller who does all the PD negotions over the cc lines and a suitable buck/boost solution which voltage/current output is preferably being controlled by the PD controller directly, although we also have an application processor available in the system. MCU’s with native PD3.0 support might also be considered as nothing is set yet in this project, I see ST has some although they seem to be not yet available.As a side note, the data-path has some very specific requirements for this project and this part is already solved. I am only looking to solve the PD3.0 part at this point.

author: dmendesf
author_rank: Frequent Contributor
timestamp: July 04, 2020, 01:20:48 am
content: Look at these:https://www.renesas.com/us/en/products/renesas-usb-power-delivery-family.html

author: tooki
author_rank: Super Contributor
timestamp: July 04, 2020, 05:47:24 am
content: I strongly suggest looking at Texas Instruments’ website. They have a massive catalog of reference designs, a large part of which are power related. They’ve got tons of USB power designs, including USB-C and USB PD.

author: MrMetthew
author_rank: Regular Contributor
timestamp: July 06, 2020, 08:02:52 pm
content: Thanks, seems like solid parts, I will look into them!!

author: MrMetthew
author_rank: Regular Contributor
timestamp: July 06, 2020, 08:03:31 pm
content: Thanks, I will go through their website and will see what I can find!!

author: bin_liu
author_rank: Contributor
timestamp: July 07, 2020, 12:32:33 am
content: CYPRESS has PD chip,
67-pin LCD Interface?  - Page 1
Forum section: electronics / projects

author: JasonWatkins
author_rank: Newbie
timestamp: November 04, 2018, 08:44:20 pm
content: I came across a few dozen 7" lcd panels that didn't quite make thecut at work. A tiny scratch gets them rejected and they were in the trash so... Yeah. I'd like to use them in several projects but I'll need to convert their 67 pin ribbon cable to HDMI or another suitable interface. Do any of you guys know what type of interface that is? Specs indicate that it's TTL but the TTL I've seen is 50-pin, not 67. The panel model is a Sharp LQ070Y3DG1A. I'd appreciate the help.

author: amyk
author_rank: Super Contributor
timestamp: November 05, 2018, 01:02:05 am
content: See attached datasheet...
68020 ? - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: December 04, 2014, 10:54:00 am
content: Hi all......Is anybody here good with Motorola CPU's. I have a board with master and slave 68000 cpu's present. I have a small interface board with a 68020 which plugs into the master socket and the system works ok with an increase in performance ! But i cannot get a 68020 to function in the slave socket ! The data-bus is 16-bits for the 68000 and therefore holds two eproms, high and low. The slave also has the same scenario, but connects to the master side via 8-bits and not 16 ! If there is anybody out there that is familiar with such designs, i would be willing to pay for somebody to make me a circuit for the slave socket and ofcourse i could provide proper information.
68k based computer in hp54502a oscilloscope - Page 1
Forum section: electronics / projects

author: ddavidebor
author_rank: Super Contributor
timestamp: November 07, 2013, 09:58:22 pm
content: Hi guysI'm trying to repair the computer inside an hp54502a oscilloscopeThe clock is ok.Sometimes all the bus are all stopped, nothing happens. Sometimes various data are on the data and address bus and the screen show horizontal lines.Do you have any suggest? It's an awesome piece of equipment, it's a pity not repair it.

author: dfmischler
author_rank: Frequent Contributor
timestamp: November 07, 2013, 10:05:17 pm
content: Do you have schematics?

author: ddavidebor
author_rank: Super Contributor
timestamp: November 07, 2013, 10:27:11 pm
content: No unfortunately

author: trackman44
author_rank: Regular Contributor
timestamp: November 08, 2013, 12:28:46 am
content: Maybe if you took pictures of the logic board and post them here we might be able to help. Also take pictures of the power supply.Will

author: Anks
author_rank: Frequent Contributor
timestamp: November 08, 2013, 03:02:00 am
content: Check the reset halt lines maybe there is a watchdog firing.

author: ddavidebor
author_rank: Super Contributor
timestamp: November 08, 2013, 06:23:30 am
content: Quote from: Anks on November 08, 2013, 03:02:00 amShould it remain high or have some type of clock?

author: Anks
author_rank: Frequent Contributor
timestamp: November 08, 2013, 10:40:01 am
content: If I remember correctly the 68K wants to see at least a 100ms low pulse at start up on the halt and reset lines then these should be held high. The reset and halt lines have other functions but I doubt they are being used. One trick is to force the reset and halt high if the watchdog is barking. This will force the processor to run but there is generally a reason why its barking but should allow you to scope the lines for bus contention and stuck data/address lines.Here is a good document on the 68Khttp://patpend.net/technical/68000/68000faq.txtSection 3.6 system control (Page 35) of the 68k user manual explains the rest and halt along with berr.http://tict.ticalc.org/docs/68kUM.pdfHope this helps
6kV 225mA ion pump supply, should i modify for variable volt ? - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: March 31, 2022, 09:25:25 am
content: https://youtu.be/wU6uBEVIUiYjust got this one.. it is a FIXED 6kV regulated supply at no load, with variable current limit and CC mode,its current settings go from uA all the way to 225mA !!since it provide both voltage and current feedback to the CPUit should be a great project to remove the CPU, add an arduino, and make it into a variable regulated voltage supply(yes i do work with hightvoltages and know what i am doing, else this is a clear DO NOT AT ALL)I also just got another one, that is all ready variable voltage, but it is only 4.7kV and much less currentit is explained herehttps://youtu.be/dfxF4nhGVQcmy old variable 10kV is broken many years ago, it was impossible to get into the high voltage parts to perform repairssince they potted it with the most hard epoxy
6lowpan module suggestion - Page 1
Forum section: electronics / projects

author: msr
author_rank: Regular Contributor
timestamp: February 13, 2014, 11:10:35 am
content: Hi guys,Can anyone recommend me a 6lowpan module?Im looking for one that I can program to avoid using an external microcontroller.Thanks

author: bingo600
author_rank: Super Contributor
timestamp: February 13, 2014, 01:54:44 pm
content: http://www.dresden-elektronik.de/funktechnik/products/radio-modules/avr-single-chip-modules/description/?L=1&cHash=c9c902ccdb43164696acccf81b62b2bd/Bingo

author: esar
author_rank: Contributor
timestamp: February 13, 2014, 09:18:09 pm
content: I've been using Atmel Zigbit modules with Contiki and IPv6/6lowpan instead of Atmel's zigbee stack, and so far they're working nicely. They're quite similar to bingo600's suggestion, being an ATmega1281, 2.4GHz tranceiver and chip antenna on a tiny little board.The only downside so far is that they're quite expensive.http://www.atmel.com/images/atmel-8226-zigbit-2.4ghz-wireless-modules-atzb-24-a2b0_datasheet.pdf
6pin on-on-on switch: a DP3T or a DPDT? - Page 1
Forum section: electronics / projects

author: k4rlhp
author_rank: Unknown
timestamp: October 02, 2018, 05:44:46 pm
content: Hi!I'm building a project and came across something unexpected (to me).It's advertised as DP3T switch on farnell...Drawing:http://www.farnell.com/cad/2291354.pdfAlcoswitch, part no. 3-1825139-9It connects center pins (the common pin) to opposite pole sides in a Z pattern when in middle position, otherwise it works like a standard DPDT switch.Would you call this a DPDT on-on-on or a DP3T?If you call it DP3T, why not call a DPDT on-off-on a DP3T since the mid position is a discreet position?Seems to me that there is some ambiguity in terminology, or maybe it's just me.Thanks.Karl

author: ajb
author_rank: Super Contributor
timestamp: October 02, 2018, 06:45:38 pm
content: DP3T implies that there are two SP3T switches, and SP3T implies one common contact that can be connected to any of three other contacts.The switch itself is a three-position DPDT switch. In options 3, 5, and 7, the center position is off. In options 11, 13, and 15 the center position is a 'staggered' on, with one side in one position and the other side in the opposite position.The notes for the diagram say "SP3T function achieved with functions 11, 13 & 15 by customer applied jumper between terminals 3 and 5", so they're showing that with external wiring you can convert the staggered DPDT switch to a SP3T (not DP3T!) switch. The diagonal line in the schematic between pins 3 and 5 is an external wire that you have to install.

author: tecman
author_rank: Frequent Contributor
timestamp: October 02, 2018, 07:16:08 pm
content: In my years of experience, this was called a DPDT-Center Off switch.DP3T implies a 3 active, unique positions,m which the switch is not.paul

author: ConKbot
author_rank: Super Contributor
timestamp: October 02, 2018, 10:31:33 pm
content: Decoding the PN with the table, shows that the switch specified is a SP3T not a DP3T switch. Look at the "function 11" on the operation chart to see how the SP3T operation is done.AJB is correct in that it's a staggered operation DPDT switch, not a normal DPDT switch, and the external jumper gives you SP3T functionality.Definitely not DP3T, but about par for the course in SP3T toggle switches, sometimes you have to add a jumper, sometimes one comes pre-attached.

author: macboy
author_rank: Super Contributor
timestamp: October 03, 2018, 03:49:03 pm
content: This switch could be wired as a forward-brake-reverse for a small brushed motor.Motor across 2,5V+ to both 1,6V- to both 3,4Or as mentioned in the datsheet, add the 3 to 5 jumper and it becomes SP3T (notDP3T) using 2 as the IN and 1,4,6 as the 3 OUTs.

author: k4rlhp
author_rank: Unknown
timestamp: October 04, 2018, 06:37:52 pm
content: I see that I'm generally right, labelling this as dp3t is incorrect. The rest is on the schematic/datasheet and sure, the switch can be used for many useful purposes just not for a dp3t. Farnell listing it as a dp3t was the unexpected part for me.
6S BMS charging - Page 1
Forum section: electronics / projects

author: Seekonk
author_rank: Super Contributor
timestamp: May 01, 2018, 03:33:40 pm
content: I've charged lots of single 18650 cell with that TP4056 (if I remember) boards. Now I need a 6S in an application. I thought there would be a 6S BMS board with charging built in. It looks like the BMS boards just do balancing and short protection. Is there a chip for charging these or do you just use constant voltage with current limit. Seems like a board for this would be common. Is there another search term?
7.3728Mhz - Page 1
Forum section: electronics / projects

author: JVR
author_rank: Regular Contributor
timestamp: October 14, 2011, 06:58:45 pm
content: Hi gents/ladies.Been reading the forum for a while and I am stuck with a question that I dont think can be answered anywhere else.Why would you clock a DSP at 7.3728Mhz? I have a dsPICdem board with this on, and I need to generate a 50us timer interrupt, but it seems to not be possible.I'll work around the problem, but would love to know the logic behind using such a random (to me) clock speed

author: Bored@Work
author_rank: Super Contributor
timestamp: October 14, 2011, 07:36:36 pm
content: Quote from: JVR on October 14, 2011, 06:58:45 pmIt is not random, it is a nice frequency. It is easily divided into clock frequencies for some common "high speed" baud rates:7372800 / 16 = 4608007372800 / 32 = 2304007372800 / 64 = 1152007372800 / 128 = 576007372800 / 256 = 288007372800 / 512 = 14400and a bunch more, which aren't too common, and aren't "high speed" (7200, 3600, ...).

author: JVR
author_rank: Regular Contributor
timestamp: October 14, 2011, 08:02:37 pm
content: That makes some sense. First time I've worked with it though.It does seem a bit daft clocking the whole micro to mach baud rates, as sampling and generation frequencies seems to take a massive accuracy knockPS: Do we need to enter the Captha for every post? Or is it just in the beginning >x posts?

author: Bored@Work
author_rank: Super Contributor
timestamp: October 14, 2011, 08:32:01 pm
content: Quote from: JVR on October 14, 2011, 08:02:37 pmTell us about the alternatives. How many independent asynchronous clock sources can your device take?In other words, that is just what is happening with such digital devices. Everything comes in steps, and something is always screwed with a single clock. Live with it. Do you think it is better to screw communication, or frequency generation? It is your job as a designer to find and use the least problematic frequency to satisfy all of your requirements.

author: JVR
author_rank: Regular Contributor
timestamp: October 14, 2011, 09:54:28 pm
content: Quote from: BoredAtWork on October 14, 2011, 08:32:01 pmTwoI guess if it wasn't 23:50 here I could just solder a 32KHz crystal in and use another timer for freq generation. Uni projects FTLThanks for clearing the 7Mhz bit up though.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 15, 2011, 01:45:17 am
content: Quote from: BoredAtWork on October 14, 2011, 07:36:36 pmif its up to me, 6.5536MHz will be nicer.there should be a better reason than that.
7.4X5.0mm DC female Connector  Where to find? - Page 1
Forum section: electronics / projects

author: Seekonk
author_rank: Super Contributor
timestamp: January 08, 2017, 02:15:08 pm
content: I'm trying to make a 12V power pack for my CPAP machine to use at my solar powered camp. Sure Icould just buy one. On another forum I was told that others have tried and failed. That just mademe want to do it more. The power pack has a modified OneWire type communication with one interesting difference. The powered device can throw a resistor from the com line to common and an A/D reads the voltage. The pull up resistor in the power pack identifies the rated power of the pack. I'm not sure this has any function now and may just be a backwards compatibility for older units. That pull up has been calculated to be 2.7K, one of the resistor values mentioned in the patent.My unit is a rental so I am not keen on just cutting up the the DC cable at this time. I've been lookingfor a compatible plug and jack so I can tie in between the units and listen in. I've ordered this7.4*5.0mm(pin inside,for DELL) barrel plug as it has three wires.http://www.ebay.com/itm/7-4X5-0mm-DC-Jack-Charger-Adaptor-Plug-Connector-Cable-for-HP-DELL-Laptop-CHCA-/122295444982?hash=item1c796065f6:g:6vsAAOSwf-VWaC4ZI can not find the matching jack for this plug in ebay or Banggood. A male/female extension cable would be acceptable. Any ideas for a source besides tearing apart a laptop?

author: kiran_shrestha
author_rank: Regular Contributor
timestamp: January 08, 2017, 02:33:21 pm
content: Is this something you are looking for .https://www.amazon.co.uk/Charger-Connector-Converter-Pavilion-15-e029TX/dp/B00PGWICAC/ref=pd_sbs_147_1/253-2610864-7162654?_encoding=UTF8&psc=1&refRID=FD507R54GA2XNKTC82Z1

author: Heszu
author_rank: Contributor
timestamp: January 08, 2017, 02:59:33 pm
content: http://www.ebay.com/itm/10-Pcs-7-4mm-x-0-6mm-x-26mm-Soldering-Female-DC-Power-Jack-Socket-Connector-/310724545090?hash=item4858a04a42:g:~ecAAOSw241Yb7NYhttp://www.ebay.com/itm/DC-Power-Jack-Socket-Cable-Adapter-Connector-Laptop-Replacement-Part-For-HP-CQ42-/172444301697?hash=item28267b3981:g:8a8AAOSwnHZYUIgjhttp://www.ebay.com/itm/like/401010091827?vectorid=229466&item=401010091827&rmvSB=truehttp://www.ebay.com/itm/Laptop-PJ180-DC-Power-Supply-Jack-Port-Adapter-for-HP-/311332244088?hash=item487cd90a78:m:mEEOVmGxjSQak6JaXj2N4IQ
7 Segment + DP Common Anode Display Driver IC - Page 1
Forum section: electronics / projects

author: cRash@101
author_rank: Newbie
timestamp: December 17, 2016, 12:04:18 pm
content: I am looking for at 7 segment + DP (8 segment) common anode display driver. I would like to connect atleast 6-8 Digits. The best I could find was AS1100 which was common cathode with 8 digits and 8 segments. I can convert it to common cathode but that would need more components which i dont want. So, plz suggest be some display driver IC's common anode.

author: mino-fm
author_rank: Regular Contributor
timestamp: December 17, 2016, 10:07:40 pm
content: You can use TPIC6B595 and current limiting resistors for each digit. There are also shift registers with constant current output to ground but at this moment I don't remember any identifier.

author: mino-fm
author_rank: Regular Contributor
timestamp: December 17, 2016, 10:20:58 pm
content: TLC5916
7 Segment LED Bezels for Projects - Page 1
Forum section: electronics / projects

author: Bryan
author_rank: Frequent Contributor
timestamp: January 01, 2016, 10:44:13 am
content: Hello :I am trying to source some bezels for 7 segment LEDS displays. they used to be common back in the 70's and 80's but can't seem to find anything anymore. If I had a CNC machine I could do some fancy cut-outs, but my filing and drilling skills are not up to snuff so trying to get a nice professional look to a project box. Failing the bezels anyone have any tricks for adding a professional look to a project when using 7 segment LEDS.Cheers

author: ataradov
author_rank: Super Contributor
timestamp: January 01, 2016, 10:58:49 am
content: Depends on your size requirements. Look at some cheap standard Chinese products, like those meters -http://www.ebay.com/itm/Brand-DC-0-30V-Blue-LED-3-Digital-Display-Voltage-Voltmeter-Panel-Meter-Gauge-/201431895516You can find them very cheap.

author: rich
author_rank: Frequent Contributor
timestamp: January 01, 2016, 04:44:20 pm
content: Digikey have open and tinted bezels, but they strangely hide them all under "optoelectronics > LCD bezels".Dave's PCB front panel method would give you a tidy cutout and silk screen text as bonus. It still leaves an un-bezelled hole but you could cover that from behind with a tinted film.For sleeker designs, a digitally printed graphic overlay with a clear (or tinted) window works. The overlays 0.2mm thick so the raised edges tend to be unsightly on a some flat panels. Solution is a bezel for the overlay! Or recess the overlay into the front panel by 0.2mm which is hard to do without a CNC but some enclosures already have the recess moulded in.I'm sure I've seen digitally printed overlays in single/low quantities at reasonable prices within the last year but I don't have any links to hand now.

author: Bryan
author_rank: Frequent Contributor
timestamp: January 01, 2016, 08:42:30 pm
content: Quote from: ataradov on January 01, 2016, 10:58:49 amThanks, forgot I bought a couple of them a few years ago and never used them, can always gut thme and just use the bezel.

author: Bryan
author_rank: Frequent Contributor
timestamp: January 01, 2016, 08:45:44 pm
content: Quote from: rich on January 01, 2016, 04:44:20 pmThanks for the Digikey source. Do you have the link for the Dave's PCB front panel method. Is hat the one where he uses his own custom end plates for aluminum chassis?

author: rich
author_rank: Frequent Contributor
timestamp: January 01, 2016, 09:14:45 pm
content: Yeah, I just remembered he is a fan of using a PCB to act as the front panel. µCalc and µCurrent being examples.It's a quick way to get access to a solder mask coloured flat plate which is machined and silkscreened to your drawings. Aesthetically it has its place, but imho not everywhere - depends what style you are aiming for :-)#644 is the extruded aluminium video you mentionµCalc #130https://youtu.be/fk8GCKO5mw4?t=532
700 MHz In-Building Coverage App & Measurement System Development - Page 1
Forum section: electronics / projects

author: sekula
author_rank: Newbie
timestamp: September 03, 2023, 03:31:11 am
content: The Public Safety Communications Research (PSCR) program is researching the development of in-building apps for RF coverage evaluation, which is critical for enhancing in-building coverage for public safety. The apps will turn a representative public safety device into an in-building measurement system and coverage evaluation system. The development of easy-to-use apps will enable the rapid collection and post processing of in-building data to assess RF coverage. This project will explore the possibility of public safety professionals doing their own measurements of Band-14 Long Term Evolution (LTE) coverage within or around any building in their jurisdictions and enable the quick identification of problem areas that will need coverage mitigation. Both first responders and the public will benefit through the identification of in-building coverage problems and enabling the mitigation of RF coverage problems. Please let me know if you have any idea?

author: Njk
author_rank: Frequent Contributor
timestamp: September 03, 2023, 09:48:27 am
content: Yet another PS application? Sounds very familiar. To my memory, it was popular topic ten years ago, when band 14 was adopted for public safety services in the US. Currently, it must be extensively researched already. Actually, every mobile phone allows to visualize a lot of parameters of received signal through engineering menu and other hooks. Just for the vendor internal purposes. So you have to contact the equipment manufacturers to get that data available for your app. Back at that time, I'd asked our intern to develop such app for project test purpose.Is it government-funded PSCR program under the NIST umbrella?
700V avalanche pulse generator experiment - Page 1
Forum section: electronics / projects

author: PartialDischarge
author_rank: Super Contributor
timestamp: October 19, 2016, 05:18:26 pm
content: Recently I came across a bunch of IRF450 (http://www.irf.com/product-info/datasheets/data/jantx2n6770.pdf), which to my surprise are repetitive avalanche rated.After reading that the famous pulse generator circuit by Jim Williams came to mind and I decided to give it a try.With an "Analog Modules" module that generates up to 1000V from 12V, I did charge a snubber cap to 700V and measured the source usinga 500Mhz, 4.6pF, 100x probe and a Rigol DS2072A 300Mhz scope.Well, the result is not bad given the crappy setup

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 20, 2016, 05:07:34 am
content: Hmm, never tried to avalanche a MOSFET for sharp edges...They have the same three-layer construction, so it should be possible. Downside: there's no separate "base" (actually substrate) contact: it's internally "diode strapped" (source tied to substrate), so you don't have any control over breakdown region.I found power BJTs (like HOTs, 2SC5700ish things) are terribly unreliable for modest surges. I don't think the junction avalanches evenly, only at a point. And once that point burns through, it becomes a modest resistance (~30kohms in my tests), which obviously doesn't help much.Avalanche being avalanche, I don't see any particular reason why MOSFETs should be more reliable, but there are much bigger differences to BJTs, so I have no idea.Tim
74 and 4000 Series Cheatsheet - Page 1
Forum section: electronics / projects

author: DJPhil
author_rank: Frequent Contributor
timestamp: September 19, 2010, 07:25:19 am
content: I whipped this up in the course of about an hour as a quick reference for salvaged and donated (Thanks, you know who you are!) logic chips. It's taken from the two lists available on wikipedia, so I haven't checked it personally to be sure it's 100% accurate. I packed it full of abbreviations, reduced the font size to 'credit card contract', and used two columns to get the whole list into three pages. My eyes aren't the best, but it seems ok after printing, no worse than the lettering on the chips themselves.I've attached it in Open Office format. You may have to play with the top and bottom margins to get it on to three pages (I used 0.70" instead of the default), as I'm not sure the format saves the margin changes.Just a quick hack together, but hopefully useful to someone. Enjoy.

author: Zero999
author_rank: Super Contributor
timestamp: September 19, 2010, 08:38:34 am
content: Interesting, just note that the 744xxxx parts are really CMOS e.g. the 744066 but it will only exist in HC or perhaps AC versions.
74161 sanity check - Page 1
Forum section: electronics / projects

author: slateraptor
author_rank: Frequent Contributor
timestamp: May 19, 2015, 09:55:13 pm
content: In need of a quick sanity check. HI/LO refer to voltage levels. Assume solid signal integrity and appropriate setup/hold timing.CURRENT STATE:CLRn = HILOADn = HID = don't careENP = LOENT = HIQ = 13Given the references below, what is Qnext?REFERENCES:TI 74'161 DatasheetTI 74F161A DatasheetSome random generic 161 VHDL model from Mentor Graphics courtesy of Google

author: magetoo
author_rank: Frequent Contributor
timestamp: May 19, 2015, 10:24:53 pm
content: Quote from: slateraptor link=topic=48137.msg676571#msg676571I happened to have the "TI Logic Guide" open, and it has a function table for the '161 that says "no change" for that case. (That'stechnicallynot what you asked, but...)

author: slateraptor
author_rank: Frequent Contributor
timestamp: May 23, 2015, 02:03:40 am
content: Unfortunately, I made the critical mistake of assuming a 74161 is a 74161 is a 74161.Turns out the Signetics variant does not operate in precisely the same manner as the linked VHDL description.This problem succeeded in driving a colleague and I batshit crazy for a week. After factoring out signal integrity and test code as possible culprits, I dropped all assumptions and tested the chip's behavior manually. What I observed was that when ENP was transitioned HI-to-LO while CLK was LO, the counter would increment once on the following clock cycle before holding count.I immediately thought, "...gotta be counterfeit lot. Surprise!" Turns out after finding theSignetics-specific datasheet, the caveat was indirectly in the fine print:QuoteBased on the quote above, the behavior I observed is technically undefined. TI's datasheet makes no mention of this whatsoever (although their timing diagram is consistent with the Signetics caveat).Lesson learned. I wonder how many bugs were a result of this subtle nuance.
74AC14N circuit suggestions - Page 1
Forum section: electronics / projects

author: SaabFAN
author_rank: Frequent Contributor
timestamp: August 25, 2015, 03:06:08 pm
content: HelloDuring the strike at the Post and DHL in germany, I bought 50 74AC14N chips for about 5€, which took so long to arrive that the seller (http://www.ebay.de/usr/sh-halbleiter?_trksid=p2060353.m2749.l2754) send me another package free of charge (the first one arrived about a week after the second package).Now I have 100 74AC14N ICs here, of which I actually need about 2... One for a Time domain Reflectometer like the one W2AEW showed, and one to perform signal conditioning on the generator-pulses of an outboard-motor to measure the RPM.But what about the rest of the chips? Do you guys have suggestions what to build? Easy stuff that can be built on a breadboard or vero-board in a less than an hour pleaseOther available chips: 555s, about 50 op-amps from the 70s and 80s, counters from the 74 and 4000 series.Bench-Equipment: MHS-5200A Signalgenerator, DS1054Z (hacked), PM3320A 200Mhz Digital Scope, KA3005P Power Supply.

author: unitedatoms
author_rank: Frequent Contributor
timestamp: August 25, 2015, 03:49:29 pm
content: One idea, you may try is to see is "Can a larger amount of less costly components perform the function of higher cost component ?". For example, can an array of 64 x 74AC14N single bit A/D channels with 11ns propagation perform the 7-bit 1GHz A/D conversion as a stroboscopic converter for repetitive signals (stroboscopic oscilloscope) ?Say, you design single bit A/D converter with 2 analog inputs: conversible input + level control input (some network of current sums, with BJTs may be), and one digital output. Then feed the level control with accurate and slow "triangle saw" from 555 - this is time domain control. Then add trigger with level, etc. Data capturing register for digital value, decoder. At the end it may work as 1GHz ADC made with lots of cheap components.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: August 25, 2015, 03:50:05 pm
content: http://bfy.tw/1T7kSorry but that's all I got other than oscillator circuits be they passive or crystal type.

author: Zero999
author_rank: Super Contributor
timestamp: August 25, 2015, 07:28:35 pm
content: Here are some simple applications.The one where it says 9V, was designed for the C version. The AC version only works to 6V.

author: C
author_rank: Super Contributor
timestamp: August 25, 2015, 08:33:38 pm
content: Two or more in series equals a time delay.Not bad as bad buss receiver.C
74c926 Why carry out at 6000? - Page 1
Forum section: electronics / projects

author: wilfred
author_rank: Super Contributor
timestamp: February 03, 2015, 10:53:23 am
content: /.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: February 03, 2015, 11:09:02 am
content: It seems like the different chips are designed for different purposes. Googling MM74C926 circuit give the answer, in the form a digital stop watch circuit. Ie, the 926 chip is designed to show seconds and hundredths of a second, given a 100 Hz clock.

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 03, 2015, 12:37:30 pm
content: Since the clock is negative edge sensitive who cares when the carry goes high? It has to go high somewhere between 0000 and 9999 anyway.So cascading does not look like a problem to me
74HC40103 Counter Setup Question - Page 1
Forum section: electronics / projects

author: rcbuck
author_rank: Frequent Contributor
timestamp: March 30, 2019, 08:13:52 pm
content: Has anyone used the 74HC40103? I want to setup a divide by 200 counter. Looking at the timing diagrams and reading the description, I'm not sure how to use the PE pin. The timing diagram shows PE being pulsed low to load the count.Can PE remain low at all times? The description says "When the PE input is low, data at the P0-P7 inputs are clocked into the counter on the next positive clock transition." This would seem to indicate the PE can't remain low since each clock pulse would just reload the PO-P7 value.If that is the case, could I tie the TC pin to the PE pin. The TC pin remains low for one full clock period so PE would be low when the next positive clock pulse happened. Or maybe insert a single buffer between TC and PE and let the propagation delay of the buffer ensure PE is low when the positive clock pulse occurs?

author: Deni
author_rank: Regular Contributor
timestamp: March 30, 2019, 08:19:30 pm
content: This should give you a hint...

author: rcbuck
author_rank: Frequent Contributor
timestamp: March 30, 2019, 08:58:20 pm
content: Thanks Deni. I didn't notice that in the data sheet. I jumped directly from the Static Characteristics page to the package outline pages.
74HC74 Power On Reset - Page 1
Forum section: electronics / projects

author: German_EE
author_rank: Super Contributor
timestamp: March 23, 2019, 07:58:49 pm
content: In a 74HC74 dual d-type FF do the two flip flops always power up in the 'reset' state with notQ high or do I need to make use of the two reset pins and apply a short 0 pulse on power up?Some experiments with an NXP part and a breadboard seem to indicate some form of reset mechanism but I am not sure here.

author: amyk
author_rank: Super Contributor
timestamp: March 23, 2019, 08:08:57 pm
content: Unless there is an explicit mention of a power-on-reset functionality, always assume that logic will power up in an undefined state.

author: Yansi
author_rank: Super Contributor
timestamp: March 23, 2019, 08:11:10 pm
content: No POR mechanism reset. use the asynchronous Set/Reset pins to init all flipflops to known states. (back in the days, chips like 7705 were used for this).

author: German_EE
author_rank: Super Contributor
timestamp: March 24, 2019, 09:35:15 am
content: OK, thank you for confirming this. One trick I found years ago for a simple power on reset was to connect a 100n capacitor from the reset pin to ground, on power up it holds the reset pin low just long enough for it to be effective.
74LS794 question - Page 1
Forum section: electronics / projects

author: Wawavoun
author_rank: Regular Contributor
timestamp: March 26, 2024, 01:44:01 pm
content: Hi All,I expect to use a 74LS794 on a Motorola 6809 bus.I hope to use it as a memory and store and read values into it. I have a /SEL signal which goes low when the LS794 address is selected.The LS794 has two controls signals :OE which enable the readback (outputs are connected to inputs when low)CK which trigger at low to high transition the register so the inputs are stored into the latches and directly send to output.Of course my bus has standard 6809 E and R/-W signals...What is the best way to connect the controls signals with minimal glue logic...I have what I think is a solution but I found it heavy...Thanks and regards.Philippe

author: Ian.M
author_rank: Super Contributor
timestamp: March 26, 2024, 02:55:18 pm
content: Logic Friday*reckons this is equivalent, which uses only 3/4 of a 74LS02. However the /OE signal has more propagation delay.* See:https://www.eevblog.com/forum/projects/74-series-logic-design-equation-optimiser/msg3170938/#msg3170938

author: Benta
author_rank: Super Contributor
timestamp: March 26, 2024, 10:08:08 pm
content: Why choose a part that's been obsolete for 20+ years, was never popular and the chances of finding NOS are close to zero?The readback function that you'd like can be done with a standard 74HCT-type register with 3-state outputs.The decoding for the latch doesn't get much simpler than three gates.

author: MathWizard
author_rank: Super Contributor
timestamp: March 27, 2024, 03:45:00 am
content: Hmm I see the 74 series doesn't like low temperatures like the freezing point of water 0C. IDK the average working temp of most parts, but yeah that's something to watch out for up here in the north.But aren't the HC parts the older slower versions, of stuff like LS parts ? Or Benta do you mean the part itself is not as good for the application ?

author: kjpye
author_rank: Contributor
timestamp: March 27, 2024, 07:37:26 am
content: Quote from: MathWizard on March 27, 2024, 03:45:00 amIf you want a wider temperature range you want the 54 series devices.No, HC devices are newer than LS. First there was the 74 series, then 74H (high speed) and 74L (low power). After that came 74S (Schottky) and 74LS (low-power Schottky—which became the go-to family). After that there were faster families like 74ALS and 74F and others. In parallel with some of the later families, a cmos version family (74C) came along, and then 74HC (high-speed Cmos) and 74HCT (with TTL signal levels).
74LVC output edge swing - Page 1
Forum section: electronics / projects

author: Oleander
author_rank: Contributor
timestamp: November 02, 2021, 01:06:33 pm
content: Hello,I am curious if the output of the 74LVC exor gate (green line) has too much of swing at the edges.Will it fit into a microcontroller's input well ?The yellow line is the input of the gate.

author: Terry Bites
author_rank: Super Contributor
timestamp: November 02, 2021, 01:48:48 pm
content: Too fast, too noisy, insufficent voltage swing?Uc Vdd is? Gate Vdd is?

author: Oleander
author_rank: Contributor
timestamp: November 02, 2021, 01:59:28 pm
content: Forgot to mention, all VCCs are 3.3V.

author: jmelson
author_rank: Super Contributor
timestamp: November 02, 2021, 02:37:25 pm
content: Quote from: Oleander on November 02, 2021, 01:06:33 pmSure, that will be no problem. Due to the fast edges from the 74LVC gate output, likely the wiggles you see are from the scope probe, and are not actually real.Jon

author: Oleander
author_rank: Contributor
timestamp: November 02, 2021, 02:48:07 pm
content: Thanks for this explanation - the probe parasitics may interact that way !

author: AndrewBCN
author_rank: Frequent Contributor
timestamp: November 02, 2021, 02:49:46 pm
content: Quote from: Oleander on November 02, 2021, 01:06:33 pmIs what you call "too much swing" the small but visible ringing in the DSO trace you posted? If so, you can control the ringing by adding a series resistor of around 100~200 Ohm to the output of the 74LVC logic gate, and/or termination resistors at the microcontroller input.I have seen much worse ringing and yet no problems at all in some circuits I have built, but of course YMMV.
74xx595 and 74xx165 sharing same serial pin? - Page 1
Forum section: electronics / projects

author: dajt
author_rank: Contributor
timestamp: May 27, 2014, 11:14:25 am
content: Hi,Trying to save pins on my Z80 computer "supervisor" I'd like to know if the following set-up would allow me to share an I/O pin for reading from and writing to sets of shift regs, and to also share a clock pin.To avoid the line used for the serial I/O being read/written by both sets of regs every time I pulse the clock I thought I'd put a 3-state buffer on the output of the 165s with it's enable pin tied to the /CE of the 165s. That way incoming data will only make it onto the shared line when the 165s are selected.Do you think the attached circuit will do what I want?Regards,David.
75R Termination for PoE - Page 1
Forum section: electronics / projects

author: sven
author_rank: Newbie
timestamp: August 17, 2019, 05:11:37 pm
content: Hi,I have a board which has Ethernet connection. Recently I wanted to extend this board with Power over Ethernet support.Since I need direct access to J4/J5/J7/J8 of the RJ-45 connector, I started looked to for a new connector which supports PoE.I came across two types of connectors, one having a 75R termination and some have not. Does anybody know why this might be necessary (or not)?My old one has termination resistors: WE 74990101210https://katalog.we-online.de/pbs/datasheet/74990101210.pdfBel 1840469-2 has none:https://www2.mouser.com/datasheet/2/643/dr-MAG-1840469-1541922.pdfPulse JXD3-0003NL has them:https://www2.mouser.com/datasheet/2/336/JXD3-0003NL-1131715.pdfWE 7499210123 has none:https://www2.mouser.com/datasheet/2/445/7499210123-922978.pdfThis one doesn't even have a tapped transformer TE 5-2337993-2:https://www.mouser.de/datasheet/2/418/NG_CD_5-2337993-2_A-1544947.pdfSven
7660 voltage inverter. No output current limit? - Page 1
Forum section: electronics / projects

author: carl0s
author_rank: Unknown
timestamp: July 15, 2018, 06:33:36 pm
content: Hi. I need to generate -5v for another LCD project. I have found the 'industry standard 7660' chip - made by all sorts of companies - TC7660, TP7660, ICL7660.Anyway, the datasheets don't seem to list a maximum current that they can supply. The only current thing listed is 'supply current', but as it is in the region of 80-200 micro amps, I am presuming that this is the current that the device itself steals, as opposed to what it can supply. Or am I misunderstanding? Surely most things (LCDs) are going to need more than 200 micro-amps ?Here's a datasheet:https://docs-emea.rs-online.com/webdocs/14f3/0900766b814f3ce5.pdf

author: oPossum
author_rank: Super Contributor
timestamp: July 15, 2018, 07:04:58 pm
content: The output voltage droops as you increase the load. So the maximum load is determined by how low a voltage you can make use of. See figure 2-7 in the data sheet.

author: Ian.M
author_rank: Super Contributor
timestamp: July 15, 2018, 07:20:48 pm
content: The abs max ratings:Quote+ note 2 (derating with temperature),Quotein conjunction with FIGURE 2-7: Output Voltage vs. Output Current, tells you all you need to know. Fig. 2-7 has curves for various input voltage from 2V to 12V (when unloaded Vout=-Vin), and as its a flying capacitor charge pump, neglecting the chip's internal operating current Iin=Iout. Therefore the difference between the absolute input and output voltages mutiplied by the load current is the dissipation. Below 5.5V you cant exceed its dissipation limit, so its short-circuit proof. Otherwise, check fig. 2-7 against max dissipation, derated for ambient temperature to see if your proposed supply voltage and load current is permissible.If there's any chance of user idiocy at supply voltages above 5.5V, a 50mA polyfuse on the output would be advisable.

author: carl0s
author_rank: Unknown
timestamp: July 15, 2018, 07:30:04 pm
content: Ah of course, since it's not a fixed voltage device they wouldn't just specify a maximum current output would they.Thanks for the help!

author: David Hess
author_rank: Super Contributor
timestamp: July 15, 2018, 08:24:01 pm
content: Usually just an output voltage versus output current graph is included for a given operating frequency and charge pump capacitance. The series resistance of the switches combine with the operating frequency and charge pump capacitance to make an equivalent output resistance.The supply current specification just refers to the operating current without any load.If higher output currents are required, then there are higher performance charge pumps than the old 7660 available. Linear Technology (now Analog Devices) makes a bunch.

author: JS
author_rank: Frequent Contributor
timestamp: July 16, 2018, 04:42:33 am
content: Quick look shows curves up to 100mA, with the sweet spot at about 5mA and working reasonable under 20mA.JS
7inch Portable DVD Player Hack - Page 1
Forum section: electronics / projects

author: giovimonto
author_rank: Newbie
timestamp: June 30, 2015, 07:35:54 pm
content: I'm currently working into a project which is about re-using this Samsung LB070W02 7inch display from an old portable dvd player.The main processor of the controller board is an Vxis VX1828 microcontroller, CVBS input only. I found the datasheets but how much i bang my head onto the table,, i can't find the composit video IN, so i hope that someone might help me. I'll link the datasheets down here.Vxis VX1828 microcontroller:http://www.daxia.com/bibis/upload/0VX1828B_Datasheet02.pdfSamsung LB070W02 LCD Display:http://www.spectrah.com/product/lcd_panel/lg_lcd_panel/lg_LB070W02.pdf

author: Skimask
author_rank: Super Contributor
timestamp: June 30, 2015, 08:22:41 pm
content: So, the pin descriptions in section 4.3 of the MCU datasheet don't help at all?

author: giovimonto
author_rank: Newbie
timestamp: June 30, 2015, 08:30:48 pm
content: I just can't understand it!If you have found the video input pin, please let me know!!

author: helius
author_rank: Super Contributor
timestamp: June 30, 2015, 08:53:58 pm
content: AIY0 thru AIY3, pins 17 to 20? It has an input switch, you need to send it a message with I2C to select an input