6 volt radio

[jacko4747]

I just bought a Roberts 6 volt Radio powered by 4 AA (1.5v) Batteries, I already have a 7.5 volt mains to dc adapter will it work or will it blow the radio ??

[Ian Stirling]

The 7.5V adaptor will probably - unless it's regulated - kill the radio, as it'll be around 10V or more off load.

If it's regulated, then there is unlikely to be a problem.

[John]

Sorry to hijack the thread but I have a similar 'problem' but the other way around. My boys got a golf game for Xmas that you connect to the TV via the Yellow and white plugs (RGB??), anyway this game needs 4 AA batteries but the instructions state an optional mains adaptor (6V) is available. I have an adaptor that does run the game but it is only 5V output other than that it is the same, centere positive, within the miliamp parameters of the game instructions, etc. The game runs fine, will it cause any problems in the long run to either the game or TV? The game will only be played occasionally.

TIA

John

[Jon]

[e-mail] declared for all the world to hear...

RCA, sometimes called "phono leads".

[mike]

"jacko4747" wrote in news: [e-mail]:

Most unlikely, especially for a quality radio.

Almost certainly it''s buffered against quite a bit of overvoltage - it's easier than dealing with millions of returns from people who've used the wrong adaptor; just the same as it'll be protected against reverse voltage.

But don't sue me!

mike

[Ron Lowe]

Composite Video over RCA Phono connectors.

It rather depends.

If the official adapter is nicely regulated to 6v, and there is no further regulation in the unit, then the electronics will run directly off the applied voltage.

So it now depends on whether the 5v adapter you have is also nicely regulated. If it is, then running it so slightly under-voltage will not harm it. The worst that could happen is that the thing might not start up or run correctly 100% reliably. If your testing shows its working fine, then its working fine.

If the 5v adapter were un-regulated, it's possible it may be running at slightly over-voltage depending on the load.

It's likely that the 6v from the official adapter ( regulated or not ) is regulated down to a lower voltage internally in the unit anyway. So long as the applied voltage is high enough for the internal regulators to come into regulation, then you can apply a fairly wide range of input voltage. In which case, you are fine.

All in all, if it works, I'd be happy enough with it.

[Dave Plowman (News)]

The 'front' games etc sockets on a TV are usually yellow for composite video, white and red for left and right audio. RGB requires a minimum of three video connectors - four if the syncs are separate. In the UK a SCART socket is usually the only RGB input.

5 volts is within the range of a usable nominal 6 volt disposable battery, so if it works fine you're ok.

[meow2222]

If the 5v is regulated, thats fine. If its unregulated, I would not let it near digital electronics chips.

NT

[Dave Plowman (News)]

And what's the 'regulation' of 4 AA cells? ;-)

[meow2222]

Its not a problem, as 4 AA cells wont go high enough to damage 74 series logic. But non-regulated warts will, thus would be risky to use.

NT

[Sylvain VAN DER WALDE]

Not the reply you expect; but Poundland do (or did recently) 6 Hyundai alkaline batteries for £1.00. The use by date is 2011. If I was in your place, I'd get a good stock of them.

Sylvain.

[Dave Plowman (News)]

Does anyone use 74 series these days?

[Ian Stirling]

There may be the odd one or several on your typical PC motherboard. One or two gates are common in other stuff.

In general, if it's mass produced, with custom silicon, they'll have put all the gates into the custom chips. Low volume stuff is common.

[Ian Stirling]

I wouldn't.

If it's a DAB radio, as most 4AA batteries will be - it uses huge amounts of power, the batteries will only last a very few hours, compared to the 20 hours you might get of an analog radio.

[Sylvain VAN DER WALDE]

A very old technology: I remember using them in a Nixie tube clock kit many years ago. That clock didn't last very long, and I never did find out if the IC's were faulty or the Nixie tubes.

Sylvain.

[Andrew Gabriel]

Certainly does damage original 74 series, which won't survive 6V. PSU's had to be crowbarred at 5.5V to save damaging 74 series boards. Some of the later series might be more tollerant, but the 5V versions were very strictly specified to 5.5V absolute max.

Some 74 families are still around, but you would be hard pressed to find the original 74 or later 74LS TTL versions of it nowadays. I used quite a bit in my youth (including the Nixie tube driver, but that never even existed in the 74LS range, only plain 74 series). Looking in my component drawers, I still have quite a lot of

74LS, 74S, and 74F series chips, but haven't used any for probably 10 years now.

The wider voltage range 74HC MOS version is still used commercially, although I've never used it myself (it was only just starting to appear when I ramped down my descrete logic circuit design/construction). I tended to use 4000 series CMOS chips when I wanted MOS parts back then.

[Dave Plowman (News)]

Current consumption for these things has gone mad. I've got an AM portable which I built from a kit in the '60s, still working, and despite going quite loud enough for most things with 0.75watts into a 7x4" speaker, the PP9 battery lasts many months used for a few hours every day. Not that it gets used much these days. ;-)

[Dave Plowman (News)]

A mate's (who was here for Xmas) father worked for STC in Torbay making Nixie tubes and won a couple of awards for improvements to the production process. They can be long lived; there was a clock at Teddington Studios in one of the older technical areas still working after more than 20 years.

[meow2222]

Why is that?

NT

[Bob Martin]

I still have boxes full of 74 & 74LS chips but haven't used any for 20+ years. I loved it - a grown-up's LEGO.