Sponsored by JLCPCB ($2 for 10 Boards): https://jlcpcb.com
To help support Julian's Postbag videos via Patreon: https://www.patreon.com/julian256
ETI Vocoder constructional project reproduced with kind permission: Wimborne Publishing Ltd. http://www.epemag.com
https://en.wikipedia.org/wiki/74181
eBay Listings:
10pcs ORIGINAL LM348N LM348 QUADRUPLE OPERATIONAL AMPLIFIERS https://www.ebay.com/itm/-/282550056828
100x Red Fork Connector Electrical Crimp Terminals for Cable 4.3mm https://www.ebay.com/itm/-/131914284638
10PCS HT7550-1 0.1A 5V Low Dropout Voltage Regulator IC LDO SOT-89 https://www.ebay.com/itm/-/401504607457
SN74LS381N SemiConductor https://www.ebay.com/itm/-/172883284288

By Julian

Youtuber, shed dweller, solar charge controller aficionado

12 thoughts on “Julian’s postbag: #120 – stuff for four different projects”
  1. Avataaar/Circle Created with python_avatars bayareapianist says:

    What a waste of money for 74381. You could program an eeprom to do the same thing. Use data bus for A and address bus for B. Use the rest of address bus lines for your function. I believe you can do 4 bit AxB also with an 8 bit eeprom.

  2. Avataaar/Circle Created with python_avatars Luis Miguel Martinez says:

    Hey Julian, I took a test last week of a subject regarding pretty much an overview of both sequential and combinational systems. I'm quite interested in the ALU design you mentioned. Would you further explore it in a video? It is actually one of the problems that were on the test and I was completely clueless on where to start.

    Thank you in advance.

  3. Avataaar/Circle Created with python_avatars Utkarsh Amitabh Srivastava says:

    I see the word postbag in the title, I click on it, it's simple.

  4. Avataaar/Circle Created with python_avatars kfishy says:

    One caveat with the HT75xx regulators: they apparently require a nominal ESR from tantalums etc, and will become unstable with purely ceramic caps. Learnt it the hard way when I tried to power ESP8266 with these and spent countless hours troubleshooting.

  5. Avataaar/Circle Created with python_avatars Rhys Powell says:

    Thanks for the shout out Julian. Great to meet you ๐Ÿ™‚

  6. Avataaar/Circle Created with python_avatars NNNI says:

    I'm trying to cope up with high school this afternoon. Believe me, things are bad here.

  7. Avataaar/Circle Created with python_avatars JasonMasters says:

    What am I doing this afternoon? Well, evening for me. I'm pulling a dud 3-cell Ni-mh battery out of a wind-to-charge torch and replacing it with a small, protected Li-ion cell. The lithium cell has a far lower mAh rating but it'll be enough for an emergency.

    Thank you for asking, Julian. ๐Ÿ˜‰

    Now I'm in something of a quandary as to what to do with the old battery pack. Do I try to find a replacement cell and repair the original battery pack, or do I scrap the lot? Or is there something else I could use the two good cells in, since only one of the cells is dead? We shall see.

  8. Avataaar/Circle Created with python_avatars Delta gaming says:

    Greets Reece and other fans

  9. Avataaar/Circle Created with python_avatars thulinp says:

    What am I doing? I should be working, therefore I watch you open your post.

  10. Avataaar/Circle Created with python_avatars DAVID GREGORY KERR says:

    It would be interesting to implement the whole VOCODER using a Texas Instruments Blackfin DSP processor chip and using the source code for a 30 channel VOCODER and compile it for the Blackfin DSP processor chip and would save a lot of hassle and space.

  11. Avataaar/Circle Created with python_avatars John Cundiss says:

    Take ya a silver marker, any light color. Put a dot on your pcb to represent direction of chip install. I admit it, I have fried a few by wrong direction. Dot on the board and the chip helps. Keep up the video's, desperate to see that vocoder.

  12. Avataaar/Circle Created with python_avatars Petri Lopia says:

    Just wondering could that "for Cable 4.3mm" mean that it's for cable that is 4.3mm and has nothing to do with how wide the fork is?

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