Timeline for Can I power TTL chips with an USB-powered MB102 board?
Current License: CC BY-SA 4.0
11 events
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| Aug 31, 2020 at 2:39 | comment | added | glen_geek | Its about time to switch from TTL to HCMOS equivalent small-scale chips. You will have to caution students to never leave inputs floating, whereas TTL could be counted on to float high (bad practice). HCMOS is much more tolerant of variations in V+ supply. And HCMOS pulls less current too. I don't envy folks doing all these last-minute COVID lab course re-writes. You're not alone - good luck | |
| Aug 31, 2020 at 0:32 | comment | added | Chris Stratton | As it is stated, this is an off-topic "usage" question. To be on-topic, you would need to provide the internal circuitry of this "MB102" product. It's not very clear what you hope to gain by using that - seemingly what you really need is just a physical translation from a USB connector to breaboard pins. | |
| Aug 30, 2020 at 23:51 | answer | added | MarkU | timeline score: 1 | |
| Aug 30, 2020 at 23:39 | history | edited | Ellen Spertus | CC BY-SA 4.0 |
Answered questions in comments
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| Aug 30, 2020 at 23:35 | comment | added | TimWescott | Well, if it'll power +5V from raw USB, it should be fine -- that wasn't apparent from the OP's question, nor a light reading of the MB102 literature. In fact "I understand that I won't get 5V out with 5V input through the USB port." | |
| Aug 30, 2020 at 23:30 | comment | added | MarkU | @TimWescott for context,the MB102 is a small assembled PCB that adapts USB power to drive a standard 2.54mm solderless breadboard supply rails; it's fairly common in Arduino/Adafruit circles. If I recall, it provides the USB +5V rail directly, and has an onboard LDO to provide +3.3V rail. | |
| Aug 30, 2020 at 23:29 | comment | added | TimWescott | The easiest thing to do if you can solder -- if a bit sporting in that it provides no protection to the USB power source -- is to get a cable, cut off the B end, strip the wires back, and solder a pigtail to the +5V wire and the ground wire. These will probably be red and black, respectively -- and you can tell by testing with a voltmeter. This is what I do to repurpose USB wall-warts as 5V supplies. | |
| Aug 30, 2020 at 23:26 | comment | added | TimWescott | You may want to add the answers to all these questions to your question, as edits. Are you supplying parts, or just instructions on the web? Is something that requires a bit of soldering OK? What level of depth of electronics assembly is OK? Are you willing to make some PC boards? | |
| Aug 30, 2020 at 23:19 | comment | added | Ellen Spertus | @TimWescott How do I get it onto the breadboard? | |
| Aug 30, 2020 at 23:14 | comment | added | TimWescott | Why not take 5V straight from USB? | |
| Aug 30, 2020 at 22:44 | history | asked | Ellen Spertus | CC BY-SA 4.0 |