Bit cable output 3.3VDC to 12VDC step up converter

Sergey KN7K

I am building small box to disconnect one Antenna when TX on another for protection (long story, you can see my other posts).

Did anyone sourced a reliable DC step up converter from 3.3V to 12V?

I have Flex recommended cable FTDI C232HM that output 3.3V.

I tried 2 different parts so far without success

1. https://www.amazon.com/dp/B09245FZ3X?ref=ppx_yo2ov_dt_b_product_details&th=1

Work fine from around 3.9V, but cannot make 12V output from 3.3V. Tried on 2 boards

2. This one adjusted fine to12V but as soon as I canned relay that consume only 34ma, voltage drops to 3V.

https://www.amazon.com/gp/product/B089JYBF25/ref%3Dox_sc_saved_image_8?smid=A3CX4TQNUXMB0L&th=1

I would appreciate some wisdom here , I mean if you figured the part that reliably works and can share :)

Thanks,

Sergey, KN7K

Sergey KN7K

It seems like in both cases input voltage drops from 3.3V to 1.9V when this boards activated, that's probably why they fail to produce a reliable output. Still looking for solution…

KD0RC

Hi Sergey, instead of a step-up converter, you might want to use a switching transistor or opto-isolator to switch 12 volts from a solid source.

Sergey KN7K

Thank you, Len.

Is there a ready board exist for purchase or do you know where can I find a schematics?

I think i found something like that

https://www.amazon.com/NOYITO-4-Channel-Optocoupler-Photoelectric-Converter/dp/B07TCW947L/ref=sr_1_3?crid=2P89CVHKAG10K&dib=eyJ2IjoiMSJ9.zoE2N0U9PErhZ21Vi8I8-jFpp0Ptx3V_WkcXRWpsZDtlkRttxmSoefF92Bh1mKJVh0beCJSEpM6pm6NEMkYOoz3wdwWunzatPH4IIGMFyRKUOHbfjsaiq2pOvD5aDpdsjI-ryYrdnozxzw8MtAC4DtQSDQEzGKUOQh4rrU8SkjQ1O-rOk2BQMapXfW20CnQOHY0WObqggqp6RikPkl6qDZ6ZEvKOPbgD7lWn1-7dH2E.3f51SRhyNEh1umIo38RRds0XsY9r1OcKWADfdVEUOsw&dib_tag=se&keywords=optoisolator%2B3.3v%2Bto%2B12v&qid=1722487020&sprefix=opro%2Bisolator%2B3.3v%2Bto%2B12v%2Caps%2C137&sr=8-3&th=1

Sergey

WX7Y

I have had to do this in the past on a Raspberry Pi that have 3.3V I/O interface and Len KD0RC has you pointed in the right direction with using Opto-Isolators.

I don't think there will be near enough drive current to trip a relay.

Some Opto-Isolators uses approx. 170ma of current to light the internal LED's in a Opto-Isolators which the BIT cable should sink just fine.

You can find a LOT of information on line about Opto-Isolators, You may have to use a 2n3904 transistor or 2n7000 FET to invert the BIT cables 3.3V so you have the right output that is in sink with the input.

Alan

Sergey

There are many opt isolated 3.3v boards, with mechanical output relays, designed to be used with Raspberry Pi GPIO pins and Adrinios. Here is one of many examples:

https://www.amazon.com/ANMBEST-Optocoupler-Trigger-Expansion-Raspberry/dp/B0B24S2P4S/ref%3Dsr_1_18?crid=JBO1EJLKYGWC&dib=eyJ2IjoiMSJ9.3ogjF_biTvutL8-YmPKuvzvZP3-kcNJWXvZB3-PmQZ339WRCR_WsY8Wk-f3naZPpYp0sQYVuytNiDmOluaA6PnXiF6ZVl4pXLEZ-iXoiDM1itsj4lAtbUJHMRXId2FRfWZ8vhJnIgnUnFxM4w4bmlbOk2uComX3tjbgHg3BwlCg09MLBKeByFRdS956AVAhL.6qrDLQOn3nlOCt2zrgA1p9019J8yk0T37Q5y-seU4XQ&dib_tag=se&keywords=3.3v%2Brelay%2Bboard&qid=1722526787&sprefix=3.3v%2Brelay%2Bboard%2Caps%2C122&sr=8-18&th=1

Alan. WA9WUD

Mike-VA3MW

Sergey

These are plug and play for $14 and they are 10A relays. Just a thought.

https://www.amazon.com/Relay-Module-Controller-Automation-Robotics/dp/B0B5LX5TVY/ref%3Dsr_1_1?crid=3HOWRB8E9LZE&dib=eyJ2IjoiMSJ9.4FDIBG86lkswyVURfjlC-KCNrb0AtprXXJ0uj39rfa6mZ7V7lKJZ7ObaT_2j4kghIATZ-eBZCCBLgorMI1RC2BRN7VIrJIThQ4vWZoLxyNTcM13J_ddk4qIrpvsCpKOK80UxU_-iV-brRUoHEba27-cwKv5-Op88JatPxZVkiZYPWRlfKk-P7SBbQd0uaxDkftmh4XUodLRWPJ-wgzIbClZDU0WRjm4Y13BZKMACBLY.Num2x_FoH-qkvb9M7l5718vn9KSO5e15S_or7DS36SM&dib_tag=se&keywords=ftdi+relay+board&qid=1722536363&sprefix=ftdi+relay+board%2Caps%2C81&sr=8-1

Sergey KN7K

Thank you all, great inputs.

One of the reason i did not pickup board with built in relay as I am not familiar with these relays and have to do some research.

My project is to use a relay to disconnect Ant 1 when TX on Ant2 and opposite - disconnect Ant2 when TX on Ant1. So, I have to check that relay can operate 1.8-50mhz without much losses at 100W.

I have a known relay's as spare that used in Steppir Antenna Relay box, so I was planning to use those as they are proven to be good even at high power.

Sergey

Mike-VA3MW

I use these relays to control the relays on the antenna switch.

Sergey KN7K

Hi Michael, that's what I am trying to avoid, as you would add time delay for each relay in chain, right?

What is your TX Delay in SSDR, 40msec?

Sergey

Mike-VA3MW

I have mine at 20ms, but most of work is on SSB for contesting, so that is plenty long enough. For CW you want it a bit longer, but make sure you follow Ken's document on setting up the entire solution.

Sergey KN7K

Thank Michael. Ordered relay board that Alan linked above, these relay are 10msec switching time, that should be good.

Thanks everyone!

Sergey

Mike-VA3MW

10-40ms is a pretty small value, and like SWR readings, I think that many people feel that it will impact their ability to make a contact in a contest.

The reality is that the other station will call back the first station that he hears a complete callsign, not the first call he starts to copy.

I only mention this for others who may be concerned with a small bit of latency.

Sergey KN7K

Completed and tested, all good, thanks

WX7Y

great job